Section 1 Guidelines for Imaging ... - CFI trainer...subjected to image analysis. (See...

Digital Photography and the Fire Investigator 1 CFITrainer.net

Required Reading

SWGIT Documents - Scientific Working Group on imaging Technology (SWGIT) Sections 1-3, 5, 6, 11 and Guidelines for Developing SOP’s and Training in Imaging Technologies.*

Almond v. The State http://www.lawskills.com/case/ga/id/99/

Kennedy v. State of Florida http://www.fdiai.org/articles/Dig%20Imagin%20FLPD.htm

Iowa I.A.I Newsletter, State v. Hayden, Wash CtApp, DivI, 2/17/98 http://www.geocities.com/cfpdlab/perspect.htm

State v. Hayden, 90 Wn. App.100, No. 38162-8-1. Division One. Feb 17, 1998*

State of Florida v. Reyes, Circuit Court of the 17th Judicial District, Case: 99-11535CF10A.*

Berg, Erik C., Legal Ramifications of Digital Imaging in Law Enforcement, Forensic Science Communications, October 2000, Volume 2, Number 4 http://www.fbi.gov/hq/lab/fsc/backissu/oct2000/berg.htm

McCoy, John, Digital Photography and the Risk of Manipulated Evidence, CHAR Patterns, Newsletter of the Wisconsin Chapter of the IAAI, April 2005.* (Note: This article is include in the reading list for this program with the permission of the Wisconsin Chapter of IAAI and the author) Section 15.2.3.4, NFPA 921, Guide for Fire and Explosion Investigations, 2004 Edition.


Additional Reading

To review all of the Scientific Working Group on Imaging Technology (SWGIT) Documents see: http://www.theiai.org/swgit/

Hodges, Keith, Admissibility of Still, Digital Photographs (images) in Criminal Trials http://www.khodges.com/digitalphoto/

Shaw, Christina, J.D., Admissibility of Digital Photographic Evidence: Should it be Any Different Than Traditional Photography? http://www.ndaa-apri.org/publications/newsletters/update_volume_15_number_10_2002.html

United Kingdom Digital Imaging Procedure http://www.crimereduction.gov.uk/cctvminisite23.htm

Litwiller, Dave, CCD vs. CMOS: Facts and Fiction, Photonics Spectra, January 2001. http://www.dalsa.com/shared/content/Photonics_Spectra_CCDvsCMOS_Litwiller.pdf

Janesick, James, Dueling Detectors, OE Magazine, February 2002. http://www.dalsa.com/shared/content/OE_Magazine_Dueling_Detectors_Janesick.pdf

NOTE: Materials identified with a (*) are included in this document. Other materials should be downloaded from the listed site by the participant.

http://www.theiai.org/swgit/

http://www.khodges.com/digitalphoto/

http://www.ndaa-apri.org/publications/newsletters/update_volume_15_number_10_2002.html

http://www.crimereduction.gov.uk/cctvminisite23.htm

http://www.dalsa.com/shared/content/Photonics_Spectra_CCDvsCMOS_Litwiller.pdf

http://www.dalsa.com/shared/content/OE_Magazine_Dueling_Detectors_Janesick.pdf


Common Terms

These common terms are used in the presentation but may not be fully explained in the program or available reference documents. Other terms or acronyms used are discussed in some detail in the supplemental materials provided with this module. CCD (charged-coupled device) – The original type of device used capture digital images dating back to the 1960s. Used in early digital cameras and many other imaging devices. The CCD image sensor is pixilated and captures the light from the image. The sensor converts the light to an electrical charge that is then transferred to a component in the device that converts the charge to voltage. The voltage for each pixel is buffered and sent from the chip to a printed circuit board located in the camera. With CCD technology most of the functions take place on the camera’s printed circuit board rather than on the imaging device. CMOS (complementary metal-oxide semiconductor) – Like the CCD, the newer CMOS device is pixilated and captures the light from the image. The conversion from charge to voltage takes place in each pixel and most functions are performed within the CMOS chip rather than on an external printed circuit board. The CMOS technology is faster and requires less power to perform its functions. Many of the newer high resolution digital cameras on the market today use this technology. ISO (International Standards Organization) – A numeric indication of the light sensitivity of a digital cameras imaging device. The higher the ISO speed the greater the sensitivity to light. This number correlates to the ISO rating of film used in conventional cameras. In digital photography high ISO speeds result in the introduction of digital noise on an image. Typical ISO ranges for prosumer and professional digital cameras will be from 100 to 1600 or greater.

SWGIT DOCUMENTS

The Scientific Working Group on Imaging Technology (SWGIT), was created to provide leadership to the law enforcement community by developing guidelines for good practices for the use of imaging technologies within the criminal justice system.

A goal of the SWGIT is to engage the entire law enforcement imaging community in the development of these guidelines. Please review these documents carefully and let us have your feedback (Instructions for sending feedback). Thank you for your consideration.

Sincerely, Richard W. Vorder Bruegge Chair, SWGIT

http://www.theiai.org/swgit/feedback.html

Version 2.3 2002.06.06

SWGIT Guidelines for the Forensic Imaging Practitioner 1

Section 1

Guidelines for the use of Imaging Technologies in the

Criminal Justice System **Released previously as “Definitions and Guidelines for the Use of Imaging Technologies in the Criminal Justice System” **

Background

Although digital imaging technologies have been used in a variety of scientific fields for

decades, their application in the criminal justice system has been relatively recent. Consequently, there has been a need to gather and disseminate accurate information regarding the proper application of this and other imaging technologies (including

silver-based film and video) in the criminal justice system.

Mission Statement

The mission of the Scientific Working Group on Imaging Technologies (SWGIT) is to facilitate the integration of imaging technologies and systems within the criminal justice

system (CJS) by providing definitions and recommendations for the capture, storage, processing, analysis, transmission, and output of images.

SWGIT Membership

The Scientific Working Group on Imaging Technologies (SWGIT) consists of over thirty photographers, scientists, instructors, and managers from more than two dozen

federal, state, and local law enforcement agencies, as well as from the academic and research communities. All SWGIT documents represent the consensus opinion of this

membership and should not be construed as the official policy of any of the represented agencies.

Purpose of this document

This document is intended to serve two purposes:

1) Provide definitions for use by personnel in the criminal justice system when discussing imaging and imaging technologies.

2) Provide preliminary general guidelines for use by personnel in the criminal justice

system as they develop specific standard operating procedures for their

respective agencies. Future documents will address other topics in the field of forensic imaging.

Part I: Guidelines

Documented Procedures

Personnel engaged in the capture, storage, processing, analysis, transmission, or output of imagery in the criminal justice system should ensure that their use of images and imaging technologies are governed by documented policies and procedures.

2 Guidelines for the use of Imaging Technologies in the Criminal Justice System

Preserving Original – Storage

The original image should be stored and maintained in an unaltered state. This includes maintaining original digital images in their native file format. Duplicates or copies should be used for working images when applicable (see Post-Capture Processing).

The following media are recommended for the preservation of original images because

of their quality, durability, permanence, reliability, and ease with which copies may be generated:

� Silver-based film negatives in 35-mm or larger format

� Write-once Compact Disk Recordable (CD-R)

� Digital Versatile Disk Recordable (DVD-R)

The following are acceptable for the preservation of original images but care must be

taken to avoid loss of data:

� Photographic prints including prints produced through instant photography

(Users are cautioned that individual photographic prints do not usually contain the full resolution and dynamic range available in original film negatives)

� Diskettes

� Magnetic tape

� Fixed hard drives

� Removable magnetic media

� Compact flash cards

� PC cards

� Smart media

� Removable magneto-optical drives

� Write-once magneto-optical drives The following are not considered to be acceptable for the preservation of original

images:

� Inkjet prints

� Solid ink prints

� Thermal wax paper prints

Version 2.3 2002.06.06


� Dye-sublimation prints

� Dry-silver prints

� Laser prints

� Electro-static prints

Preserving Original: Post-Capture Processing

Film: Can process the original if the processing is non-destructive.

Analog Video: Recommend minimal processing of original to avoid degradation of signal. If original is used, a copy should be made prior to processing and analysis.

Digital: Make a duplicate image and use the duplicate as the working image.

Documentation of Image Processing

Techniques common to traditional darkrooms and digital imaging stations, such as

cropping, dodging, burning, color balancing, and contrast adjustment that are used to achieve an accurate recording of an event or object, are standard processing steps. When the results of these steps are visually verifiable, documentation of such steps is

not considered mandatory except when the image is subjected to image analysis.

Techniques, such as unsharp masking, multi-image averaging or integration, and Fourier analysis, that are used to increase the visibility of specific details in an image at the expense of other image details are standard processing steps. However, the use of

such steps should be documented in the case notes in sufficient detail that comparably trained personnel can repeat the steps and produce the same output when the image is

subjected to image analysis. (See "Recommendations and Guidelines for the use of Digital Image Processing in the Criminal Justice System").

Verification of Original and Processed Images

Personnel who captured the original image or were present at the time the original image was captured can verify that the image is a true and accurate representation.

Any processed image subjected to image analysis should be documented with an image

processing log. An image not subjected to image analysis does not need a log. It is recommended that the image processing log document steps such as: dodging,

burning, color balancing, contrast adjustment, unsharp masking, multi-image averaging or integration, and Fourier analysis. The use of such steps should be documented in the

case notes in sufficient detail that comparably trained personnel can repeat the steps and produce similar output.

Preserving Images: Chain of Custody

Agencies must develop chain of custody policies for archiving images. For digital images, the chain of custody should document the identity of the individuals who had custody and control of each primary digital image file from the point of

capture to the creation of the archive image. Once the file has been archived, the chain of custody should document the identity of the individuals who had custody and control


of custody should document the identity of the individuals who had custody and control of the archive image.

Guidelines for Software

Software used in the processing and analysis of digital images should produce

consistent results, permitting comparably trained personnel to achieve similar results.

LEGAL NOTE: Manufacturers of software used for image processing may be required to make the software source code available to litigants, subject to an appropriate

protective order designed to protect the manufacturer=s proprietary interests. Failure

on the part of the manufacturer to provide this information to litigants could result in the exclusion of imaging evidence in court proceedings. This should be considered when

selecting software.

Guidelines for Image Compression

Original images and images expected to undergo image analysis should not be subjected to lossy compression. If compression is necessary, lossless compression is

strongly recommended. If lossy compression must be used, then the highest quality option is recommended. Note that if lossy compression is used, critical image information could be lost and unwanted artifacts introduced as a result of the

compression process. Repeated saving of a file using lossy compression may exacerbate the loss of image information.

Guidelines for Image Capture

Image capture devices should be capable of rendering an accurate representation of

the item or items of interest. Different applications will dictate different standards of accuracy. At a minimum, the following should be considered when selecting appropriate devices:

� Characteristics (size, movement, location, etc.) of the scene, item, or items of

interest

� Lighting of the items of interest

� Dynamic range of the scene

� Time constraints

� Required end product(s)

When documenting major crime scenes it is strongly recommended that a camera capable of manual override, with interchangeable lenses, off-camera flash, and a tripod mount be used as the primary capture device. Conventional silver-based film in 35-mm

format or larger is recommended for use as the primary media in this case. This documentation may be supplemented by video and/or digital still imaging.

It should be recognized that some agencies may wish to utilize equipment other than

that recommended above. In such circumstances, the agencies should demonstrate and document that the selected equipment is adequate to meet the agency's anticipated needs.

Version 2.3 2002.06.06


Further information and additional SWGIT recommendations relating to different law

enforcement field applications may be found in the SWGIT document "Guidelines for Field Applications of Imaging Technologies in the Criminal Justice System".

Further information and additional SWGIT recommendations regarding image capture devices for Forensic Laboratory applications are not yet available.

Guidelines for Image Output

An output device should be capable of producing an accurate representation of the

input image. The following should be considered in the selection of output devices:

� Final use of image


� Longevity/permanence of output image

� Spatial resolution required

� Range of colors and brightness to be produced

Guidelines for Image Transmission

Received images should accurately reflect the transmitted images. The following should be considered in the selection of transmission methods and devices:

� Final use of image


� File size

� Security of transmission

� Integrity of transmission

� Hardware and software compatibility of transmitters and receivers

� File format compatibility

Part II: Elements of Standard Operating Procedures (SOPs)

The following should be considered when formulating standard operating procedures:

Title: The title should be a descriptive name for the procedure.

Purpose: Why, when, and by whom the procedure is used.

Equipment/Materials/Standards/Controls: Identifies what items are required to

perform the procedure. This may include protective equipment, hardware, software, and configurations.


Procedures: A step-by-step description of how the procedure is conducted. If

appropriate, instructions should include precautions to be taken to minimize degradation.

Calibration: Describes any steps required to ensure the accuracy and reliability of the procedure. Where applicable, instrumentation setup and calibration procedures should

be documented.

Calculation: Describes any mathematical operations that are applicable to the procedure.

Limitations: Describes any actions, interpretations, or equipment that are not appropriate for the procedure.

Safety: Identifies and addresses potential hazards in the use of the procedure.

References: Identifies documents both internal and external to the user agency regarding the procedure, related procedures, and principles behind them.

Part III: Quality Assurance

Personnel utilizing images and imaging technologies in the criminal justice system

should implement quality assurance programs to ensure that results achieved are repeatable and valid. As part of these programs, performance checks and corrective actions should be documented.

Equipment

Where applicable, equipment utilized in imaging should be checked regularly for proper performance and calibration, and findings documented. Where applicable, an end-to-end system check for consistency within specified system parameters should be

performed on a regular basis and whenever modifications are made to the system. All

equipment should be maintained according to the manufacturers= specifications and

recommendations as contained in the operating manuals.

When a piece of equipment or a system falls outside the specifications and recommendations, the equipment or system should be taken out of service until it has

been corrected. Evaluation of equipment and system checks should be documented inclusive of corrective actions.

Software If software errors that significantly affect the results of a processing step are detected,

then corrective actions should be taken. If the manufacturer identifies software errors and provides corrective remedies for them, the remedies should be implemented before the software is used again. Once corrective actions have been taken, an end-to-end

system check should be performed prior to putting the system back into operation.

Personnel All personnel utilizing imaging technologies shall be trained and tested for competency

and proficiency in the agency=s standard operating procedures and the operation of the

relevant imaging technologies. A formal training program should be documented and

maintained, with the results of competency and proficiency tests documented.

Version 2.3 2002.06.06


maintained, with the results of competency and proficiency tests documented. Proficiency testing should be repeated on a regular basis or when significant changes in

hardware or software are made.

Part IV: Training

Issues relating to training in imaging technology are addressed in the SWGIT document "Guidelines and Recommendations for Training in Imaging Technologies in the Criminal Justice System".

Version 1.2 2001.12.06


Section 2

Consideration For Managers

Introduction

This document provides managers with considerations generated by SWGIT members. The migration to new imaging technology may significantly affect current work

processes and should be done only after examining current operating procedures and completing a needs assessment. This should involve the participation of the organizations imaging and/or subject matter experts. Examining current operating

procedures is the crucial first step in implementing new imaging technology.

Consideration 1: Needs Assessment1

� Prior to selecting digital imaging technology, current practices must be examined

to determine if there is a need to replace or enhance existing technology. � Consideration should be given to a hybrid imaging system where some or all of

the current equipment is used in conjunction with a new technology.

Consideration 2: Cost Analysis1

� Prior to selecting a digital imaging system, a cost-benefit analysis must be

conducted to determine the cost justification of a system purchase and to determine the possible advantages and disadvantages to the agency with its implementation.

� This analysis would allow a financial comparison between the current and

proposed imaging systems to make a procurement decision.

� To determine a cost estimate, the following components should be considered:

system hardware, software, and maintenance; application software; communications hardware and software; training; project management; facilities

upgrades and site preparation; and staffing and miscellaneous costs.

� A typical cost justification includes the following major areas: a study of current

operations, proposed system architecture, equipment pricing, and financial indicators, including a payback period.

Consideration 3: Image Resolution1

� When determining resolution requirements, the intended usage, data storage requirements, and the need for accurate reproduction of the image must be considered.

2 Consideration for Managers

Consideration 4: Image Storage2

� Original images must be preserved on separable media.

� The selection of a storage media may depend on budget considerations for the

agency. Each has its own advantages and disadvantages.

Consideration 5: Image Compression3

� Compression affects image quality and should be considered carefully.

� Lossy compression, such as JPEG, can result in the loss of critical details. The use of this type of compression may render an image unsuitable for forensic analysis.

Consideration 6: Equipment Evaluation

� Information used to evaluate suitability of new imaging technology should

include feedback from agencies currently using the equipment in similar applications, product reviews, and vendor specification sheets.

� Prior to making a final selection, require a demonstration of new imaging technologies using representative samples of casework.

� Do not rely solely upon prepackaged demonstrations.

Consideration 7: Standard Operating Procedures (SOPs)

� SOPs must be developed to ensure consistency, quality, integrity, and repeatability of the process.

� A staff member should be responsible for the overall project management, system administration, and maintenance of the SOPs.

� It is the responsibility of a staff member, rather than vendors and manufacturers, to maintain written documentation of system procedures and

SOPs, including access and security policies and procedures.

Consideration 8: Training4

� Initial and continuing training in imaging technology is required.

Version 1.2 2001.12.06


Consideration 9: Recurring Costs

� Administrative managers should be aware of the cost of maintaining and upgrading imaging systems. Unless these costs are factored into the budget, the

system is in danger of becoming obsolete. Some agencies annually budget approximately 15 percent of the original system acquisition cost for upgrades, training, and maintenance.

Consideration 10: Legal Considerations

� SOPs should be designed to protect the integrity of the images.

� The user should be familiar with how the rules of evidence apply.

1See SWGIT Guidelines for Field Applications of Imaging Technologies 2See SWGIT Guidelines for the Use of Imaging Technologies in the Criminal Justice System 3 See SWGIT Recommendations and Guidelines for the Use of Digital Image Processing in the Criminal Justice System 4See SWGIT Guidelines and Recommendations for Training in Imaging Technologies in the Criminal Justice System

Version 2.3 2001.12.06


Section 3

Guidelines for the Field Applications of Imaging

Technologies in the Criminal Justice System

Introduction

The purpose of this document is to:

� Provide specific recommendations and guidelines for the use of imaging technologies in law enforcement field applications.

� Describe the advantages and disadvantages of silver-based film cameras, instant

photography cameras, digital still cameras, video cameras, and hybrid imaging systems in law enforcement field applications.

� Provide general guidelines for preparing agency-specific imaging technologies

standard operating procedures (SOPs) for law enforcement field applications.

� Provide imaging equipment recommendations.

This document addresses the photographic documentation of events or subjects that are not in a controlled environment (e.g., forensic laboratory or studio).

The field applications addressed in this document include the following imaging:

� General crime scene photography

� First responder (FR) photography

� When crime scene photography personnel will not be called

� Prior to arrival of crime scene photography personnel

� Surveillance photography

� Tactical surveys

� Hazardous materials (HAZMAT) crime scene photography

� Aerial photography

� Accident scenes

� Arson photography

� Autopsy photography

2 Guidelines for the Field Applications of Imaging Technologies in the Criminal Justice

System

� Bomb scene photography

� Mass disaster photography

� Search warrant photography

� Gang-related graffiti photography (FR)

� Field mug shots and tattoos (FR)

� Victim photography

Advantages and Disadvantages of Major Image Capture

Technologies in Field Applications

The selection of an acquisition device (camera) is driven by the purpose and

requirements of the end product. Therefore, the final use of the image should determine the choice of the camera.

The recommendations for primary and secondary image capture devices are dependent

on current technology and may change subject to changes in technology. These recommendations are made based on the practical experience of the SWGIT membership in the acquisition and analysis of the images discussed herein. Agencies

should decide what technologies are best suited to meet the requirements of their mission-specific tasks. As long as an agency can demonstrate and document that its

choice of technologies is adequate to meet its anticipated needs, the agency should not feel required to adhere to the SWGIT recommendations.

Silver-Based Film Cameras

It is strongly recommended that a camera capable of manual override, with interchangeable lenses, off-camera flash, and a tripod mount be used as the primary

capture device along with conventional silver-based film in 35 mm format or larger as the primary capture media for evidentiary photography/imaging.

Advantages of silver-based film cameras in field applications:

� Highest resolution of available image capture options

� Highest dynamic range of available image capture options

� Best color range of available image capture options

� Most flexibility of currently available image options

� Most durable storage medium

� More readily available in the field than video or digital storage media

Version 2.3 2001.12.06


Disadvantages of silver-based film cameras in field applications:

� Need for separate processing/printing facilities

� Relatively long processing time

� Environmental hazards generated by processing byproducts

� Preprocessing fragility (i.e., temperature, humidity, x-ray effects, expiration)

� No means of immediate image evaluation (with the exception of instant film)

Discussion

Resolution: The best measure of resolution is the evaluation of output imagery, which

is the product of a series of steps. However, since this document is devoted to field applications, the following discussion is restricted to camera evaluation only. Users

should verify resolution by visually examining images of test targets in their specific environments.

SWGIT uses the following definitions of resolution: "Measure of capability to delineate picture detail;" and "The ability of a photographic system to record fine detail." These

definitions are a subset of those found in ANSI/A Technical Report TR26-1993: Resolution as it Relates to Photographic and Electronic Imaging.

Traditionally, film manufacturers measure resolution in terms of line pairs per millimeter

(LP/mm) or lines per millimeter. Figure 1 illustrates how a line pair consists of a black line and an adjacent white line. Lines

per millimeter refers to each line (black or white), thus there are always twice as many

lines as there are line pairs over a given distance.

Manufacturers of digital cameras frequently describe image size in terms of number of

pixels. As stated in ANSI/A TR26-1993, "There is a common practice of referring to digital

resolution as simply the total number of pixels within a frame or field, or alternately as the number of pixels in the horizontal and vertical

directions. Alone, this information is useful to indicate the amount of data that can be handled in a single field at a given moment,

but tells nothing about the unit's ability to resolve spatial information." (Note that the words frame and field in the quote refer to a photographic field of view. These should not be confused with the terms used in video technology.)

The ability to resolve spatial information can only be determined by testing a specific

imaging system. In order to compare technologies, the total information that can be represented in the sensor is discussed. This constitutes an upper limit to the actual

Figure 1 Conventional Film Resolution

in Terms of Line Pairs per Millimeter

(Lp/Mm) or Lines per Millimeter.


System

represented in the sensor is discussed. This constitutes an upper limit to the actual achievable resolution.

It is possible to directly

compare the maximum amount of information that can be represented by any

two sensors by comparing the total number

of pixels per frame. To compare film to the sensors in digital cameras

(CCD/CMOS), it is necessary to relate line pairs per frame to pixels per frame. Figure 2 illustrates how, under

ideal conditions, two pixel columns(or rows) represent one line pair. Common film types encountered in law enforcement field applications have optimal

resolutions in the range of 40 - 160 line pairs per millimeter. Black and white films typically used at crime scenes have resolutions at the upper end of this range. Color

films used at crime scenes have resolutions at the lower end of this range.

A single frame of 35 mm ISO 200 color film is 36 mm wide by 24 mm high. With a resolution of 50 line pairs per millimeter, such a frame can resolve the following: 36mm x 50 LP/mm = 1800 line pairs horizontally and 24mm x 50 LP/mm = 1200 line

pairs vertically.

The equivalent number of pixels in a single frame is then calculated: 1800 line pairs x 2 pixels/line pair = 3600 pixels horizontally and 1200 line pairs x 2 pixels/line pair = 2400 pixels vertically. This represents a total of 3600 x 2400 =

8,640,000 pixels.

A digital camera with a detector that is 3040 x 2008 pixels in size contains more than six million (6,104,320) pixels. This is referred to as a 6-megapixel camera. There is a tradeoff between the field of view and the resolution that can be represented

by a sensor. If the field of view is held constant, then the resolution will vary with the number of pixels. If resolution is held constant, then the field of view will vary with the

number of pixels.

Figure 2 Relating Line Pairs per Frame to Pixels per Frame under theoretically ideal conditions.

Each Line Pair corresponds to two-pixel columns.

Version 2.3 2001.12.06


If the field of view is held identical for both sensors

above (35 mm ISO 200 color film and a 6-

megapixel CCD), the film, with 40 percent more pixels than the CCD

(8.64 million versus 6.1 million), will provide an

improvement in resolution of approximately 20

percent.

Alternatively, if the resolution is held constant for both sensors, the film will cover a field of view that is 40 percent larger than the CCD, as illustrated by Figure 3.

The resolution that can be

achieved in a digital camera will be lower than the upper

limit (ideal conditions) discussed above. Some research has found that it

takes approximately four pixels to capture and

reproduce a line pair under test conditions, instead of the representation by two

pixels. Using this standard, the pixel resolution of film

is effectively doubled. The practical result of using four pixels per line pair leads to

the comparisons in Table 1 and Figure 4.

NOTE: Discussing the resolution of video systems

is beyond the scope of this document. SWGIT will address issues relating to video resolution in future documents.

To compare the size of images generated from each of these sensors, a common output resolution must be defined. A conservative divisor of 200 pixels per inch (ppi) is

generally used to determine the output size. Table 2 lists the size of the images generated using the sensor resolutions in Table 1.

In the above discussion, only film and digital sensors were considered. In reality, an image is captured and later displayed using an entire system in which several factors

may affect the resolution of the particular image. The quality of the optics (lens or lenses) used to focus the image on the sensor plays an extremely important role and

may greatly limit the overall resolution of the system. Also, differences in display

Figure 3 Comparison of Field of View 35 mm ISO 200 Color

Film versus 6-Megapixel CCD for Constant Resolution.

Figure 4 Relative Field of View for different sensors at

comparable resolution.


System

may greatly limit the overall resolution of the system. Also, differences in display methods may limit or enhance the perceived resolution.

CCD sensors often achieve color acquisition by using one sensor array with pixel cells of

alternating color sensitivity. Thus the overall resolution of the image will be less than the specified number of pixels on the sensor. One way to ameliorate this situation is to use a camera that contains three CCDs instead of one. This allows one to have a

separate CCD for each primary color, red, green, and blue. Therefore, for the same specified number of pixels at the sensor, a three-CCD camera will provide higher

resolution than a single-CCD camera. Two other factors that can affect resolution include the contrast in the scene and noise.

In this context, contrast refers to the apparent difference between the brightest and darkest parts of the scene. As contrast increases, resolution increases. Noise refers to

random variations that limit the fidelity of detection and reproduction systems, such as the granularity of photographic images. As noise increases, resolution decreases. Identifying the specific effects of these factors on each of the sensors discussed above

is beyond the scope of this document.

Dynamic Range: The difference between the brightest highlight and darkest value that a sensor (film or CCD) can detect and record in a single image. Negative film provides

two to four f-stops more than most digital cameras. This increased dynamic range allows capture of both shadow and highlight details in a single frame of film. These same details might require several different images (at different capture settings) when

recorded with a digital camera.

Color Range: The range of colors that can be detected by a sensor compared to normal human vision. Negative film has a color range that is superior to CCDs.

Flexibility: The selection of speeds and types of film available. Silver-based photography provides a wider selection of film speeds and types than digital cameras.

Film can be selected for specific applications in the field, and the film speed or type can be changed on-site to meet specific needs.

Instant Print Cameras

Advantages of instant print cameras in field applications:

� Immediacy of the final image (instant viewing/verification of image)

� Operational security (all processing is in-house)

Disadvantages of instant print cameras in field applications:

� Limited resolution of image

� Production of copies requires multiple steps and can reduce image quality

� High cost per image

� Manual override, interchangeable lenses, or off-axis flash rarely offered

Version 2.3 2001.12.06


Digital Cameras

Advantages of digital cameras in field applications:

� Immediacy of the final image (instant viewing/verification of image)

� Ability to transmit and disseminate image with minimum of intermediate steps

� On-site image management

� Potential for on-site printing

� Operational security (all processing is in-house)

� Environmental impact more friendly than film

Disadvantages of digital cameras in field applications:

Battery or power supplies:

� Environmental impact

� Availability � Power conversion

� Limited availability of storage media (available only from specialized stores)

� Storage media subject to damage from electromagnetic fields

� Image acquisition subject to electromagnetic interference

� Hardware and software can be proprietary and incompatible among

manufacturers

� Legacy file problem (evolution of technology, including hardware and software, may impact ability to access archived images over time)

Video Cameras

NOTE: Fixed camera video surveillance systems are not addressed in this document.

They will be addressed in future SWGIT documents.

Advantages of video cameras in field applications:

� Real-time motion record capability

� Immediacy of image (instant viewing/verification of image)

� Ability to transmit and disseminate image with minimum of intermediate steps


System

� More environmentally friendly than film

� Ability to print in the field

� Ability to synchronize and capture audio

Disadvantages of video cameras in field applications:

� Battery or power supplies:

� Environmental impact � Availability

� Power conversion

� Some high-quality storage media available only from specialized stores

� Storage media subject to damage from electromagnetic fields

� Image acquisition highly subject to electromagnetic interference

� Resolution of still images is less than that of digital or silver-based capture media

� Limited color fidelity (VHS and 8 mm formats, in particular)

� Reduced media lifetime

� Automatic compression in some formats

� Weight and portability of equipment may be an issue

Notes on video formats:

� VHS and 8 mm formats are the most commonly available formats but have the worst signal-to-noise ratio of any video format (greatest amount of noise).

� Super VHS and Hi-8 formats are the second most commonly available formats and have somewhat better signal-to-noise ratio than VHS.

� Beta SP and MII formats are professional-broadcast quality and are the best analog format available.

� Digital video quality varies, the high end is better than analog systems.

Hybrid Imaging Systems

A hybrid system is the combination of silver-based photography and digital imaging technology that typically involves the conversion of silver-based film or print images to digital images through the use of scanners. Hybrid imaging systems incorporate some

of the benefits of both film and digital image technologies and are recommended for those agencies and organizations seeking to add digital imaging technologies to their

photographic resources.

Version 2.3 2001.12.06


photographic resources.

Advantages of hybrid imaging systems in field applications:

� Shortens darkroom time for producing prints

� Maintains high-quality original film images

� Offers flexibility of digital image processing

� Enables easy electronic transmission of images

� Enables image analysis

� Simplifies case file management

� Enables the use of a variety of output devices

� Permits the production of copies from prints generated through instant photography

Disadvantages of hybrid imaging systems in field applications:

� Separates processing/printing facilities

� Has a relatively long processing time

� Generates environmentally hazardous byproducts

� Demonstrates a preprocessing fragility (i.e., temperature, humidity, x-ray effects, expiration)

� Has no means of immediate image evaluation (with the exception of instant film)

Guidelines for Standard Operating Procedures (SOPs)

General Guidelines for a Crime Scene Photography SOP

TITLE: Crime Scene Photography SOP

PURPOSE: To permanently document, by qualified personnel, evidence and other details at a crime scene for future reference

NOTE: Crime scene photography generally requires the ability to:

� Record information that crime scene personnel may not know was important at the time the images were captured

� Deal with varying lighting and physical conditions


System

� Accurately represent the details and colors in a scene

� Get close-up and wide-angle images with accurate spatial relationships

Crime scene photography is usually a time-limited activity when there is only one opportunity to correctly complete the task. Depending on the nature of the crime or

incident, conditions at a crime scene may dictate the selection and use of differing equipment and techniques.

EQUIPMENT: (Image Capture Devices)

� Silver-based film cameras are recommended for use as the primary image capture device. The minimum recommendation is a 35 mm (SLR) camera

capable of manual override, interchangeable lenses, off-camera flash, and tripod mount

� Digital still imaging can be used in a supplementary capacity (see Digital

Cameras). Digital still imaging can be used as the primary image capture device when the performance of the equipment can be shown to meet anticipated needs

� Video imaging can be used in a supplementary capacity. S-VHS, Hi-8, or better-

quality formats are recommended. It is suggested that cameras have the ability to incorporate external/wireless audio, the ability to disable on-camera audio, and incorporate/disable in-camera image stabilization (See Video Cameras)

� Other standard photographic equipment as necessary

PROCEDURES: Agencies should follow agency-specific step-by-step instructions for

documenting crime scene evidence. CALIBRATION: If necessary, agencies should develop procedures specific to their

needs.

CALCULATIONS: If necessary, agencies should develop procedures specific to their needs.

LIMITATIONS: See Advantages and Disadvantages of Major Image Capture Technologies in Field Applications

SAFETY: Agencies should develop procedures specific to their needs.

REFERENCES: Agencies should refer to agency-specific documentation and manufacturers' manuals.

General Guidelines for a First Responder (A) SOP

The only images taken are those taken by the first responding officer(s).

TITLE: First Responder Photography SOP

PURPOSE: To document conditions found at an incident by the first law enforcement official(s) on the scene where a crime scene photography unit or specialist will not be

Version 2.3 2001.12.06


official(s) on the scene where a crime scene photography unit or specialist will not be requested.

NOTE: Examples may include: domestic violence incidents, traffic accidents, minor

property crimes, and other incidents as defined by agency-specific policies. Photography generally is not the first responder's primary responsibility, and the first responder may have only a minimal amount of photography training.


� Silver-based media film camera. Minimum recommendation is a 35 mm camera with flash and close-up capability

� Digital still imaging. The minimum recommendation is for a camera with more than 1600 x 1200 pixels (>2 megapixels), on-camera viewer, close-up capability,

flash, and removable storage media

� Video imaging can be used in a supplementary capacity. S-VHS, Hi-8, or better-quality formats are recommended. It is suggested that cameras have the ability to incorporate external/wireless audio, disable on-camera audio, and

incorporate/disable in-camera image stabilization (See Video Cameras)


PROCEDURES: Agencies should follow agency-specific step-by-step instructions for documenting crime scenes.

NOTE: Images from separate incidents should be clearly delineated through a change

of storage media or through proper documentation. CALIBRATION: If necessary, agencies should develop procedures specific to their

needs.


LIMITATIONS: Successful capture of close-up images will require adhering to manufacturers' specifications. Images captured digitally typically have a limited

enlargement capability that is less than those captured using 35 mm film (See Advantages and Disadvantages of Major Image Capture Technologies in Field

Applications). Successful capture of images also requires utilization of fresh media (e.g., film that is not past expiration and has been stored properly) and well-maintained equipment.




System

General Guidelines for a First Responder (B) SOP

Images taken by the first responding officer(s) prior to arrival of a crime scene photographer.

TITLE: First Responder Photography SOP

PURPOSE: To document conditions found at an incident by the first law enforcement official(s) on the scene prior to the arrival of a crime scene photographer

NOTE: This guideline is directed toward documenting transient conditions that might be lost prior to the arrival of crime scene photographers. Examples include situations in

which evidence must or might be moved, lost, or altered. Photography generally is not the first responder's primary responsibility, and the first responder may have only a minimal amount of photography training.


� Silver-based media film camera. The minimum recommendation is 35 mm camera with flash, close-up capability

� Digital still imaging. The minimum recommendation is for a camera with more than 1600x1200 pixels (>2 megapixels), on-camera viewer, close-up capability,

flash, and removable storage media

� Video imaging can be used in a supplementary capacity. S-VHS, Hi-8, or better-quality formats are recommended. It is suggested that cameras have the ability to incorporate external/wireless audio, disable on-camera audio, and

incorporate/disable in-camera image stabilization (See Video Cameras)


PROCEDURES: Agencies should follow agency-specific step-by-step instructions for documenting crime scenes.

NOTE: Images from separate incidents should be clearly delineated through a change of storage media or proper documentation.

CALIBRATION: If necessary, agencies should develop procedures specific to their

needs. CALCULATIONS: If necessary, agencies should develop procedures specific to their

needs.

LIMITATIONS: The successful capture of close-up images will require adhering to manufacturers' specifications. Images captured digitally or with video typically have a limited enlargement capability that is less than those captured using 35 mm film (See

Advantages and Disadvantages of Major Image Capture Technologies in Field Applications). Successful capture of images also requires using fresh media (e.g., film

that is not past expiration and has been stored properly or new, unused videotapes) and well-maintained equipment.

Version 2.3 2001.12.06


and well-maintained equipment.



General Guidelines for a Surveillance Photography SOP

TITLE: Surveillance Photography SOP

PURPOSE: To document acts and individuals engaged in those acts as they occur.

NOTE: Surveillance activities may involve highly specialized techniques and equipment that require technical training and knowledge and are best accomplished by trained

specialists.


� Silver-based media film camera. The minimum recommendation is a 35 mm camera with capability to disable both the flash and infrared auto-focus transmitter

� Digital still imaging. The minimum recommendation is for a camera with a minimum pixel resolution of 2000 x 1500 pixels (3 megapixels), capability to accommodate long telephoto lenses, and disable the flash and infrared auto-

focus transmitter. In covert surveillance situations, illumination of the photographer by the LCD screen may compromise safety

� Video imaging can be used in a supplementary capacity. S-VHS, Hi-8, or better-

quality formats are recommended. It is suggested that cameras have the ability to incorporate external/wireless audio, disable on-camera audio, and incorporate/disable in-camera image stabilization (See Video Cameras)


NOTE: State laws may limit the legality of audio taping. Check local statutes for legality of all surveillance activities.

SPECIALIZED EQUIPMENT: Night vision or thermal imaging equipment

PROCEDURES: Agencies should follow agency-specific step-by-step instructions for documenting crime scenes. If audio is used, simultaneous recording of audio with video on the same media and testing of the system is strongly recommended.



needs.


System

LIMITATIONS: The successful capture of images sufficient for identification of

depicted individuals and/or objects (e.g., license plates) will require close attention to the selection and appropriate use of equipment. Images captured digitally or with video

typically have a limited enlargement capability that is less than those captured using 35 mm film (See Advantages and Disadvantages of Major Image Capture Technologies in Field Applications). The successful capture of images also requires utilization of fresh

media (e.g., film that is not past expiration and has been stored properly or new, unused videotapes) and well-maintained equipment.



General Guidelines for a Tactical Survey SOP

TITLE: Tactical Survey SOP PURPOSE: To document conditions at a location so that plans can be made for future

law enforcement activities

NOTE: This type of photography is directed at obtaining general information regarding the physical layout and major contents of a location in preparation for law enforcement activities.


� Silver-based media film camera. Minimum recommendation is 35 mm camera

� Digital still imaging. Minimum recommendation is for a camera with more than

1600 x 1200 pixels (>2 megapixels)

� Video imaging can be used in a supplementary capacity. S-VHS, Hi-8, or better-quality formats are recommended. It is suggested that cameras have the ability

to incorporate external/wireless audio, disable on-camera audio, and incorporate/disable in-camera image stabilization (See Video Cameras)


PROCEDURES: Agencies should follow agency-specific step-by-step instructions for documenting crime scene locations.



needs.

LIMITATIONS: Location-specific limitations may apply.

Version 2.3 2001.12.06



REFERENCES: Agencies should refer to agency-specific documentation and

manufacturers' manuals.

General Guidelines for a HAZMAT Scene Photography SOP

TITLE: HAZMAT Scene Photography SOP

PURPOSE: To permanently document, by qualified personnel, evidence and other details at a crime scene that may contain biological, chemical, and/or radiological

hazards NOTE: A careful assessment of each HAZMAT scene is necessary prior to committing

any personnel or equipment. The means for inserting, removing, and sanitizing equipment and personnel from a scene should be planned prior to initial entry. HAZMAT

scene photography generally requires:

� Recording information that the crime scene personnel may not realize was important at the time the images were captured

� Contending with varying lighting conditions

� Accurately representing all of the details and colors in a scene

� Getting close-up and wide-angle images with accurate spatial relationships

HAZMAT crime scene photography is usually a time-limited activity when there is only

one opportunity to correctly complete the task. This type of photography usually involves the use of protective clothing and gear that will make the operation of photographic equipment more difficult.


� Silver-based film cameras are recommended for use as the primary image capture device. Minimum recommendation is 35 mm (SLR) camera capable of manual override, interchangeable lenses, off-camera flash, and tripod mount. If protective housings are not available but needed, disposable, waterproof 35 mm cameras

may be necessary for some HAZMAT scene photography

� Digital still imaging can be used as the primary means when the performance of the equipment can be shown to meet anticipated needs or when contamination

issues may preclude the use of silver-based media. Otherwise, digital still imaging can be used in a supplementary capacity (See Digital Cameras). Minimum

recommendation is for a 3-megapixel camera

� Video imaging can be used in a supplementary capacity. S-VHS, Hi-8, or better-quality formats are recommended. It is suggested that cameras have the ability


System

to incorporate external/wireless audio, disable on-camera audio, and incorporate/disable in-camera image stabilization (See Video Cameras)


SPECIALIZED EQUIPMENT: Equipment for protecting personnel and camera systems.

PROCEDURES: Agencies should follow agency-specific step-by-step instructions for

documenting crime scene evidence. CALIBRATION: If necessary, agencies should develop procedures specific to their

needs.


LIMITATIONS: Protective equipment will hamper the use of some equipment, and conditions may not permit the use of other equipment (e.g., flash, film). (See

Advantages and Disadvantages of Major Image Capture Technologies in Field Applications)



General Guidelines for an Aerial Photography SOP

TITLE: Aerial Photography SOP

PURPOSE: To document locations, activities, and geographical relationships using

aircraft as a platform NOTE: Aerial photography may involve highly specialized techniques and equipment

which require technical training and knowledge and is best accomplished by trained specialists.


� Silver-based media film camera. The minimum recommendation is 35 mm camera capable of manual operation

� Digital still imaging. The minimum recommendation is for a camera with a pixel resolution of 3000 x 2000 pixels (6 megapixels) or higher

� Video imaging can be used in a supplementary capacity. S-VHS, Hi-8, or better quality formats are recommended. It is suggested that cameras have the ability

to incorporate and/or disable external/wireless audio and on-camera audio. It is strongly recommended that image stabilization be used (See Video Cameras)

Version 2.3 2001.12.06



SPECIALIZED EQUIPMENT: Night vision or thermal imaging equipment

PROCEDURES: Agencies should follow agency-specific step-by-step instructions for aerial photography activities.

CALIBRATION: If necessary, agencies should develop procedures specific to their needs.


LIMITATIONS: Check the legality of all surveillance activities. Images captured digitally

or with video typically have a limited enlargement capability that is less than those captured using 35 mm film (See Advantages and Disadvantages of Major Image Capture Technologies in Field Applications). Successful capture of images also requires using

fresh media (e.g., film that is not past expiration and has been stored properly, and new, unused videotapes) and well-maintained equipment.


REFERENCES: Agencies should refer to agency-specific documentation, manufacturers' manuals, and local statutes.

General Guidelines for an Accident Scene Photography SOP

� When agency policy does not require that crime scene photography personnel respond—see General Guidelines for a First Responder (A) SOP.

� When agency policy requires that crime scene photography personnel respond--

see General Guidelines for Crime Scene Photography SOP.

General Guidelines Covered Under General Guidelines for Crime Scene

Photography SOP

� General Guidelines for an Arson Scene Photography SOP

� General Guidelines for Autopsy Photography SOP

� General Guidelines for a Bombing Scene Photography SOP

� General Guidelines for a Mass Disaster Scene Photography SOP

� General Guidelines for a Search Warrant Photography SOP


System

General Guidelines Covered Under General Guidelines for a First

Responder SOP

� General Guidelines for a Gang Related Graffiti Photography SOP

� General Guidelines for a Field Mug Shots and Tattoos Photography SOP

� General Guidelines for a Victim Photography SOP

Table 1. Comparison Pixel Resolution of Capture Media

Media/Sensor Sensor Size and

Resolution

Number of Pixels Equivalent

(at 4 pixels/line pair)

35 mm ISO 100 Black and White Film

36 mm x 24 mm at 100 lp/mm

14,400 x 9,600

35 mm ISO 200 Color Film

36 mm x 24 mm at 50 lp/mm

7,200 x 4,800

Instant Prints 92 mm x 73 mm at

10 lp/mm 3,680 x 2,920

6 Megapixel CCD 3,040 x 2,008 3,040 x 2,008

3 Megapixel CCD 2,008 x 1,504 2,008 x 1,504

.3 Megapixel CCD 640 x 480 640 x 480

Table 2. Comparison of Output Size for Capture Media

Media/Sensor

Number of Pixels Equivalent

(at 4 pixels/line pair)

Output Size in Inches

(at 200 pixels per

inch)

35 mm ISO 100 Black and

White Film 14,400 x 9,600 72 x 48"

35 mm ISO 200 Color Film 7,200 x 4,800 36 x 24"

Instant Prints 3,680 x 2,920 18.4 x 14.6"

6 Megapixel CCD 3,040 x 2,008 15.2 x 10"

3 Megapixel CCD 2,008 x 1,504 10 x 7.5"

.3 Megapixel CCD 640 x 480 3.2 x 2.4"

Version 1.2 2002.06.06


Section 5

Recommendations and Guidelines for the Use of Digital

Image Processing in the Criminal Justice System

Purpose

The purpose of this document is to provide recommendations and guidelines for the use

of digital image processing in the criminal justice system. The objective is to ensure the successful introduction of forensic imagery as evidence in a court of law. This document

includes brief descriptions of advantages, disadvantages, and potential limitations of each major process.

Background

Digital image processing is an accepted practice in forensic science. It is the position of the Scientific Working Group on Imaging Technologies (SWGIT) that any changes to an

image made through digital image processing are acceptable in forensic applications provided the following criteria are met:

� The original image is preserved

� The processing steps are logged when they include techniques other than those used in a traditional photographic darkroom

� The end result is presented as an enhanced image, which may be reproduced by applying the logged steps to the original image

� The recommendations of this document are followed

Introduction

This document addresses digital image processing and related legal considerations in

the following four categories:

� Image enhancement

� Image restoration

� Image compression

� Image analysis

When using digital image processing techniques, use caution to avoid the introduction of unexplainable artifacts that add misleading information to the image and the loss of image detail that could lead to an erroneous interpretation. Any processing techniques

should be applied only to the working image.

2 Recommendations and Guidelines for the Use of Digital Image Processing in the Criminal

Justice System

The successful introduction of forensic imagery as evidence in a court of law is dependant upon the following four legal tests:

� Reliability

� Reproducibility

� Security

� Discovery

Image Enhancement

Image enhancement is any process intended to improve the visual appearance of an image. This includes processes that have a direct counterpart in the conventional silver-based photographic laboratory and those that can be accomplished only by using a

computer.

Traditional Enhancement Techniques Traditional enhancement techniques are techniques that have direct counterparts in traditional darkrooms. They include brightness and contrast adjustment, color

balancing, cropping, and dodging and burning. These traditional and acceptable forensic techniques are used to achieve an accurate recording of an event or object.

Brightness adjustment is used when the image is too bright or too dark. If the image is made too bright, there is a risk of loss of detail in light areas. If the image is made too

dark, there is a risk of loss of detail in the dark areas.

Color balancing is the adjustment of the color components of an image. The purpose of color balancing is to render the colors in the scene faithfully. Improper color balance adjustment can render colors inaccurately, and objects will appear to have the wrong

color when compared to the actual subject.

Contrast adjustment is used when the image lacks sufficient contrast. If the image contrast is increased too much, there is a risk of loss of detail in both light and dark

areas. Cropping is used to remove that portion of the image that is outside the area of

interest.

Dodging and burning have the same effect as brightness adjustment but are used in localized areas.

Spotting traditionally has been used to remove artifacts due to dust and scratches on the negatives, but it is not considered to be an acceptable practice on any forensic

image. Note: The use of spotting and cropping techniques may come under scrutiny in a court

of law. Specific agency policies should address the use of these techniques.

Version 1.2 2002.06.06


Nontraditional Enhancement Techniques

Some nontraditional image enhancement processes are used and accepted by a variety

of scientific fields such as medicine, aerospace, and cartography. These processes have no direct counterpart within traditional silver-based photography. In fact, only recently have they been applied within the forensic environment; therefore, their general

acceptance may be subject to challenge.

Examples of nontraditional processes discussed here are color processing, linear filtering, nonlinear contrast adjustments, pattern noise reduction, and random noise reduction.

Color processing includes color space transformations, pseudocoloring, and hue and

saturation adjustments. These techniques can be used to modify the color characteristics of objects within an image.

Caution: Application of these techniques can compromise the color fidelity of the image.

Linear filtering techniques include sharpening, deblurring, edge enhancement, and

deconvolution. They are used to increase the contrast of small detail in an image. If a low degree of enhancement is used, the image will remain an accurate representation of the scene. If a high degree of enhancement is used, the image may no longer be an

accurate representation of the overall scene, though still may be useful as an adjunct for interpretation of small details.

Caution: A high degree of enhancement can also increase the visibility of existing noise and artifacts.

Examples of noise include film grain, snow appearing on a TV screen, or random color

dots are shown in Figure 1, on the next page.


Justice System

Figure 1. This example illustrates the effects of linear filtering. Left: original image; Middle: blurred image; Right: sharpened image.

Nonlinear contrast adjustments include gamma correction, grayscale transformation,

curves, and look-up tables. These are an extension of traditional photographic sensitometric techniques and are used to adjust the contrast in selected brightness ranges within the image.

A nonlinear contrast adjustment can be used to bring out details in the shadow areas of

an image without affecting the highlight areas. Caution: A severe adjustment can cause loss of detail, color reversal, and the

introduction of artifacts, see Figure 2 on the next page.

Version 1.2 2002.06.06


Figure 2. This example shows nonlinear contrast adjustments. Left: original image; Middle: enhancement of shadow and highlight areas, at the expense of midrange tones; Right: enhancement of midrange tones, at the expense of shadow and highlight areas.

Pattern noise reduction filters identify repeating patterns in the image and allow the user to selectively remove them. This type of filter can be used to remove patterns

such as fabric weaves, window screens, security patterns, and halftone dots. Caution: Overuse of this technique can cause selective removal of relevant image

detail. Random noise reduction techniques include such filters as low pass, blurring, median, and despeckling. They are used to reduce the contrast of small detail in the

image in order to suppress random noise. Caution: Overuse of this technique can cause loss of relevant detail.

Considerations for the Application of Image Enhancement Techniques

Question: What type of image must not be enhanced? Answer: A primary or original image. Discussion: Because a primary or original image represents the first instance where

the image is recorded onto any media, or it is an accurate and complete replica of the primary image, it must not be altered or modified. Enhancements are performed only

on working images. Question: Is it necessary to document the enhancement process used to produce an

enhanced image? Answer: The need to document the enhancement process is determined by the

process used.


Justice System

process used. Discussion: Documentation of enhancement steps is not necessary when using

traditional darkroom techniques. When using nontraditional image enhancement techniques such as unsharp masking or random noise reduction, enhancement steps

should be documented in the case notes in sufficient detail to enable another comparatively trained individual to repeat the steps and produce the same output when the image is subjected to image analysis.

Question: In a legal setting, are enhanced images discoverable?

Answer: Yes. Discussion: All images may be discoverable. In cases where images are enhanced, both the original and the enhanced image, along with associated documentation, may

be discoverable.

Question: Who is responsible for testifying about an enhanced image? Answer: The person doing the enhancement or a person skilled in and knowledgeable about the enhancement process that was used.

Discussion: The person who performed the enhancement is best qualified to testify about the enhancement techniques used. However, there may be occasions where the

court will require the assistance of additional subject-matter experts.

Question: Are there legal ramifications associated with the software used specifically for image enhancement? Answer: Yes.

Discussion: Some considerations may include:

� Have the particular functions within the software been accepted by the scientific community?

� Does the software perform as the manufacturer purports?

� Has the use of this software been reviewed by the judicial system?

� Does the software have "plug-ins" that are produced by another manufacturer?

� Is the enhancement process repeatable and reliable?

Image Restoration

Image restoration is any process applied to an image that has been degraded by a

known cause (e.g., defocus or motion blur) to partially or totally remove the effects of that degradation.

Limitations are imposed on this technique by any noise in the image and by the fact that information that has been totally lost cannot be replaced. Often partial restoration

can be successful even when total restoration is impossible. Restoration Techniques

Blur removal is a filtering technique designed to partially or completely remove an image blur imposed by a known cause. It differs from the image enhancement filtering

processes because the blur removal filter is designed specifically for the process that blurred the particular image under examination. Examples include defocus and motion

Version 1.2 2002.06.06


blurred the particular image under examination. Examples include defocus and motion blur, since these blurring phenomena can be described mathematically. Thus, a specific

filter can be designed to compensate for each blur. The degree to which a blur can be successfully removed is limited by noise in the image, the accuracy with which the actual blurring process can be described mathematically, and the fact that information

has been totally lost and cannot be replaced. Often partial deblurring can be successful even when total deblurring is impossible.

Color balancing is the extension of grayscale linearization to a color image. It is the adjustment of the color components of an image. The purpose of color balancing is to

render the colors in the scene faithfully. For example, a color test target having known colors can be placed in the scene prior to recording the image. Then a grayscale

transformation (nonlinear contrast stretch) can be designed for each color channel (red, green, and blue) in order to place the different colors on the test target in their proper relationship. It is commonly assumed that the color of other objects in the scene will be

rendered accurately as well. Improper color balance can render colors inaccurately, causing objects to appear to have the wrong color.

Geometric restoration is the removal of geometric distortion from an image. Its purpose

is to restore the proper spatial relationships among the objects in the scene. It can be used for the removal of geometric distortion, such as that introduced by a curved mirror or a fish-eye lens. It differs from image warping in that the geometric

transformation is designed specifically for the process that distorted the particular image under examination. The degree to which geometric distortion can be successfully

restored is limited by the accuracy with which the actual distortion process can be described mathematically and the fact that information that has been totally lost (e.g., hidden behind another object or obscured from the camera) cannot be replaced. Often

partial geometric restoration can be successful even when exact geometric restoration is impossible.

Grayscale linearization is the adjustment of brightness relationships among the objects in a scene. The purpose of grayscale linearization is to render faithfully the different

brightness values in the scene. For example, a monochrome test target having known gray values can be placed in the scene prior to recording the image. Then a grayscale

transformation (nonlinear contrast stretch) can be designed to place the different gray values on the test target in their proper relationship. It is commonly assumed that the other objects in the scene will be put in their proper brightness relationship as well.

Improper grayscale linearization can render brightness values inaccurately so that objects may appear brighter or darker than they actually appeared when the image was

recorded. Warping, unlike other image restoration processes, changes the spatial relationships

among the objects in an image. It is analogous to printing a photograph on a rubber sheet, then stretching the sheet in different directions and then tacking it down.

Warping can be used, for example, to remove perspective from an image or to "unroll" a poster that was wrapped around a pole. Used improperly, it can distort the natural appearance of the objects in a scene.


Justice System

Considerations for the Application of Image Restoration Techniques

Question: What type of image must not be restored? Answer: A primary or original image.

Discussion: Because a primary or original image represents the first instance where the image is recorded onto any media, or it is an accurate and complete replica of the primary image, it must not be altered or modified.

Question: Is it necessary to document the restoration process?

Answer: Yes. Discussion: Documentation of restoration steps is always required.

Question: Are restored images discoverable in legal proceedings? Answer: Yes.

Discussion: All images may be discoverable. In cases where images are restored, both the original and the restored image, along with associated documentation, may be discoverable.

Question: Who is responsible for testifying about a restored image?

Answer: The person doing the restoration or a person skilled in and knowledgeable about the restoration process that was used.

Discussion: The person who performed the restoration is best qualified to testify about the restoration techniques used. However, there may be occasions when the court will require the assistance of additional subject-matter experts.

Question: Are there legal ramifications associated with the software used specifically

for image restoration? Answer: Yes. Discussion: Some considerations may include:

� Have the particular functions within the software been accepted by the scientific

community? � Does the software perform as the manufacturer purports?



� Is the restoration process repeatable and reliable?

� Has the degradation process been accurately modeled?

Image Compression

Digital images produce a large amount of data to be stored. Image compression techniques reduce the storage requirements by making image data files smaller.

Compression Processes Lossless compression reduces file size by removing redundant information. Because the

redundant information can be replaced in order to display the image, lossless compression results in no loss of information. Lossless compression does not alter the

Version 1.2 2002.06.06


compression results in no loss of information. Lossless compression does not alter the content of an image when it is decompressed. An example of a file format that uses

lossless compression is the graphical interchange format (GIF). Lossy compression achieves greater reduction in file size by removing both redundant

and irrelevant information. Because the irrelevant information (as determined by the compression algorithm) cannot be replaced upon reconstruction of an image for display,

compression results in some loss of image content as well as the introduction of artifacts. The degradation occurs each time the image is saved in a lossy file format. Higher compression ratios result in the loss of more information. Normally the degree

of compression can be specified. Depending upon the application, lossy compression may render an image less useful.

Caution: Compression should be used with care to avoid material degradation of the image. Additionally, the compression settings used by one camera or

software program may not be the same as the compression settings used by another camera or software program.

The commonly used Joint Photographic Experts Group (JPEG) image storage format

employs image compression. It is applied to the image in 8-pixel by 8-pixel blocks. Normally, the degree of compression can be specified prior to storing the image. At high compression ratios, JPEG could remove important image detail and introduce

blocking artifacts as the block boundaries become visible. (See Figure 3) Digital cameras often create digital images in JPEG format, so that some compression is

unavoidable. The degree of compression should be set low enough that important image content is not lost or obscured by artifacts.


Justice System

Figure 3. Left: original image; Middle: the result of JPEG compression (compression ratio = 15:1); Right: the result of edge enhancement after compression.

Considerations for the Application of Image Compression Techniques

Question: What type of image must not be compressed? Answer: It depends on the end use and need.

Discussion: In instances where the primary or original image is already compressed, it should not be further compressed using lossy compression processes; additional data will be lost. Sources of compressed primary images may include electronic booking

photographs, some types of digital camera images, and images downloaded from the Internet or E-mail. The file format is not an indicator of the compression history for an

image. For example, a TIFF file may have been previously compressed in a lossy file format (JPEG). Be aware that the end use of any image may change over time, and the use of compression may become problematic. Images intended for laboratory analysis

should not be compressed using a lossy process.

Question: Is it necessary to document the compression history of an image? Answer: It depends on the intended use of the image. Discussion: The type and degree of compression may become an issue in a judicial

proceeding. Documentation may be necessary in a court of law when argued that compression might have introduced artifacts or relevant information was lost.

Question: Who is responsible for testifying about a compressed image? Answer: The person doing the compression can testify about the settings used to

compress an image. Discussion: Questions concerning the actual compression process should be referred

Version 1.2 2002.06.06


Discussion: Questions concerning the actual compression process should be referred to individuals who possess sufficient technical expertise to explain the specific process.

Quantitative Image Analysis

Quantitative image analysis is the process used to extract quantitative (measurable)

data from an image, whereas cognitive image analysis is the process used to extract visual information from an image. This section discusses quantitative analysis only.

Quantitative image analysis requires proper calibration of the image. In a digital image the pixel spacing must be known in order to extract accurate size measurements.

Objects that are different distances from the camera will have different pixel spacing. The accuracy of the extracted measurements will depend upon the accuracy of calibration. Caution: The use of image compression can degrade the accuracy of

subsequent quantitative image analysis.

An example of a quantitative image analysis might be if a circular object in an image includes 314 pixels, and the area covered by a single pixel is one square millimeter, then one can conclude that the area of the object is 314 square millimeters. Similarly, if

the distance between the adjacent pixels in an image of a document is 0.02 inches, and the length of the document is 340 pixels, then it must be 340 times 0.02, or 6.8 inches

long. These examples do not consider perspective distortion. Quantitative Image Analysis Techniques

Colorimetry is the quantification of the color of an object. Image authentication verifies that the original image has not been altered.

Photogrammetry is the science involving methods, techniques, and analytical procedures used to make accurate measurements of distances and/or sizes of objects from photographic images.

Photometry is the measurement of light values of objects in an image.

Considerations for the Application of Image Analysis Techniques

Question: Which types of image should be subjected to quantitative image analysis? Answer: A working image.

Discussion: Because a primary or original image represents the first instance where the image is recorded onto any media, or it is an accurate and complete replica of the

primary image, it must not be altered or modified. Question: Is it necessary to document quantitative image analysis?

Answer: Yes. Discussion: Documentation of quantitative image analysis steps is required in

sufficient detail to enable another comparably trained individual to repeat the steps and produce the same conclusions.

Question: Are analyzed images discoverable? Answer: Yes.

Discussion: All analyzed images, documentation, and conclusions may be discoverable.


Justice System

Question: Who is responsible for testifying about an analyzed image? Answer: The person doing the analysis or a person skilled in and knowledgeable about

the analysis performed. Discussion: The person who performed the analysis is best qualified to testify

concerning the techniques used. However, there may be occasions where the court will require the assistance of additional subject-matter experts.

Question: Are there legal ramifications associated with the software used specifically for image analysis?

Answer: Yes. Discussion: Some considerations may include:

� Have the particular functions within the software been accepted by the scientific community?

� Does the software perform as the manufacturer purports?



� Is the analysis repeatable and reliable? Additional Imaging Considerations

Question: Where does image processing take place, in the field or in a controlled

environment? Answer: Both. Discussion: Whereas most image processing takes place in a controlled environment,

some image processing, such as photogrammetry and image compression, may take place in the field.

Question: Who performs image processing? Answer: Photographers, analysts, and technicians.

Discussion: The person performing the processing must be properly trained.

Question: What are file management processes? Answer: File management processes are the capture, storage, indexing, retrieval, and archiving of image files.

Discussion: Agencies and organizations should establish file management procedures for managing image files for use at a later date.

Question: Does image processing alter images? Answer: Yes.

Discussion: The purpose of image processing is to alter the images in a controlled, predictable, and repeatable manner. Image processing does not mean that the input

image is overwritten during the process. Forensic image processing should only be performed on working images.

Version 1.2 2002.06.06


Guidelines for Digital Image Processing Standard Operating Procedures

The purpose of image processing procedures is to apply processing techniques intended

to enhance, restore, compress, and/or analyze digital images. The success of the processing of digital images is measured against the four legal tests: reliability,

reproducibility, security, and discovery. To achieve success, standard operating procedures should be followed. Appendix A is a sample standard operating procedure.

Guidelines for Equipment The agency should address the following minimum hardware and software

equipment requirements. Hardware:

� Input/capture device

� Image processing systems

� Output devices

� Storage/archive

Software:

� Image management

� Image processing

Guidelines for Procedures Agencies should establish specific step-by-step procedures for image processing

according to agency requirements using SWGIT guidelines. These procedures should address the following as a minimum:

� Capture

� Processing

� Storage/archive

� Image management

� Security

� Output

Guidelines for Calibration If necessary, agencies should develop calibration procedures specific to their needs.

Guidelines for Calculations If necessary, agencies should develop calculation procedures specific to their needs.


Justice System

Guidelines for Limitations

Agencies should take into consideration agency-specific budget, equipment, management, and accrediting agency requirements.

Guidelines for Safety Agencies should develop safety procedures specific to their needs.

Guidelines for References

Agencies should maintain its agency-specific documentation, manufacturers' manuals, and SWGIT guidelines.

Guidelines for Training Agencies should document procedures to ensure sufficient training to afford

competence and proficiency with applicable image processing. Refer to the Guidelines and Recommendations for Training in Imaging Technologies in the Criminal Justice System.

Version 1.2 2002.06.06


Appendix A Standard Operating Procedures for Latent Print Digital Imaging

Latent Print Units Laboratory Division

1. Purpose

1.1. This document sets forth Latent Print Units (LPU) specific procedures for latent print digital imaging.

2. Changes and Review

2.1. The Section Chief and Unit Chiefs are the only persons who may authorize changes to this document.

2.2. The appropriate LPU personnel who handle evidence which may be digitally processed must review the LPU Standard Operating Procedure for Latent

Print Digital Imaging (SOP-LPDI).

3. Responsibilities

3.1. The Section Chief, Unit Chiefs, Team Supervisors, and Program Managers are

responsible for ensuring that LPU personnel adhere to the evidence-handling procedures stated in the LPU Evidence Control Policy.

3.2. LPU personnel are required to handle evidence slated for latent print digital

imaging in accordance with the procedures set forth in the LPU Evidence Control Policy.

4. Sending Evidence to the Latent Photography and Digital Imaging Group

4.1. LPU Specialists will determine if latent print digital image processing for enhancement purposes is needed after the appropriate silver based

photographic procedures have been performed.

4.1.1. Specialists will initiate a separate Latent Print Digital Imaging

Requisition form (LPDIR) for each item of evidence and will ensure all information is accurate. (Appendix B)

4.1.2. Specialists will submit the form and appropriately sealed evidence to the Latent Photography and Digital Imaging Group (LPDIG).

5. Evidence Receiving in Latent Photography and Digital Imaging Group

5.1. LPDIG personnel will ensure that the LPDIR form and the evidence are submitted properly, and will sign for receipt.

6. Digital Image Capture

6.1. Upon receipt, the LPDIG Supervisor or designee will assign the submission to a

photographer trained in digital imaging.

6.1.1. The assigned photographer will initiate a LPU Latent Print Digital


Justice System

Imaging Processing form (LPDIP). (Appendix C)

6.1.2. The assigned photographer will use a digital image capture device to record the image of the latent print(s) in question and save the

original image for each latent print using the file name structure to be defined.

6.1.3. The photographer will record the file name(s) assigned to the

image(s) on a separate LPDIP form for each latent print. If the evidence is no longer needed, it will be stored in the evidence

storage facilities in the LPDIG. 7. Digital Image Processing

7.1. The LPDIG Supervisor and Technology Development and Support Group (TDSG) Supervisors or respective designees will determine which specialist

or photographer should perform the processing. 7.2. If the case specialist is not a digitally trained specialist, the

specialist/photographer assigned will then contact the case specialist to

arrange a time for the processing, so that the case specialist can be present when the processing is performed.

7.3. All processing steps will be recorded in the order they are performed either on a LPDIP form or within the computer program, if the program has that

capability. 7.4. Once the case specialist is satisfied that the best possible image has been

achieved, the image will be saved with a second file name assigned and

recorded on the LPDIP form. 7.5. The case specialist will receive the original of the LPDIR and LPDIP forms

along with all appropriate computer printouts for case documentation. A hard copy of both the original and processed images will also be provided for comparison purposes.

7.5.1. If no improvement results from this process and no images will be

utilized by the case specialist, the original forms will be returned to the case specialist for case documentation, and a notation on the worksheet must be made that reflects the results of this effort. No image files will be

stored when no improvement results.

8. Storage and Archiving of Images

8.1. All images, both original and processed, will be stored temporarily on the

hard drive of the imaging station until the examination(s) is completed. 8.2. A backup copy of the images will be created weekly by the LPDIG Supervisor

or designee and maintained in a locked cabinet within the LPU LPDIG until the examination(s) is completed.

8.3. Once the examination(s) is completed, the LPDIG Supervisor or designee will

record the resultant images on two Digital Video Disks (DVD's) or Compact Disks (CD's) along with any associated case information. One DVD/CD will

be designated a working copy and kept with the digital imaging equipment in a locked cabinet. The second DVD/CD will be designated as archival and kept in a locked cabinet within the TDSG.

Version 1.2 2002.06.06


8.3.1. The LPDIG Supervisor or designee will enter the appropriate DVD/CD serial numbers on both the LPDIR and LPDIP forms, return

the originals to the case specialist, and file the duplicate copy of the LPDIP form within the locked cabinet along with the archival DVD/CD.

8.3.2. The DVD/CD's will be filed by the engraved serial number in numerical order in the above-mentioned cabinets. A database will be

maintained by the LPDIG Supervisor.


Justice System

APPENDIX B

Version 1.2 2002.06.06


APPENDIX C

Version 1.2 2001.12.06


Section 6

Guidelines and Recommendations for Training in Imaging

Technologies in the Criminal Justice System

Purpose

The consistent and reliable use of silver-based, video, and digital imaging technologies in the criminal justice system requires the competent and appropriate training of personnel.

The purpose of this document is to provide guidelines and recommendations for such training.

It should be recognized that some agencies may choose to provide training other than what is recommended in this section. In such circumstances, those agencies should

demonstrate and document that the training selected is adequate to meet their anticipated needs.

Introduction

Personnel in the criminal justice system who work with images must be aware of the capabilities and limitations of specific imaging technologies. Those engaged in the

production or the use of images should be aware of the procedures commonly followed within the law enforcement community and should strive to meet or exceed

these recommendations. They should also endeavor to maintain awareness of new developments. In support of these goals, the following recommendations are offered to personnel engaged in the production of images:

� Define and employ quality assurance programs to ensure the implementation of valid and reliable procedures for the task.

� Maintain proficiency by pursuing continuing education courses in imaging technology.

� Maintain awareness of legal developments relating to the use of imaging

technologies in the criminal justice system.

Definitions of Categories

Several categories of imaging technology training relevant to the criminal justice system as well as the categories of the system users who would benefit from the training are identified and defined as follows:

Categories of Training

� Awareness: Training designed to provide the student with a general knowledge of the major elements of a given imaging technology including specific product

capabilities

2 Recommendations for Training in Imaging Technologies in the Criminal Justice System

� Skills and techniques: Training designed to provide the student with the ability to competently use specific imaging equipment

� Knowledge of processes and relationships: Training designed to provide the

student with an understanding of imaging technology and the ability to apply that technology to various applications

� Court procedures: witness testimony: Training designed to provide the student

with the ability to present reliable imaging technology-based testimony in court

� Court procedures: case preparation: Training designed to provide the student with the ability to prepare and review accurate and reliable imaging technology-based

evidence

� Continuing education: Training designed to provide the student with additional and updated training in imaging technologies

� Specialized applications: Training in specific disciplines or in specialized areas

� Proficiency: Proficiency training incorporates a number of components:

� Required levels of skill and knowledge for a job category should be identified by the agency. These levels should be driven by the requirements of the specific tasks to be accomplished.

� A course should be designed by the agency or its agent, to provide the skills

and information necessary for the agency's personnel to attain competency in those skills

� If determined to be necessary by the agency, a proficiency test should be

developed and administered to test these skills.

� Different levels of proficiency tests may be developed depending on the level of skill and experience of the personnel.

Categories of Users

� Management: Includes personnel who are responsible for setting agency policies

and/or making budget decisions

� Command/Supervision: Includes personnel who supervise and/or direct personnel engaged in the use of imaging technologies

� Law Enforcement Officer: Includes personnel who use imaging technologies as a minor component of their routine duties. If the person is routinely involved in the

basic photographic documentation of crime scenes, then this person would fall into the crime scene technician category

Version 1.2 2001.12.06


� Crime Scene Technician: Includes personnel for whom imaging is a major component of their routine duties. Crime scene technicians are divided into two

categories. Level 1 technicians routinely perform only basic photographic or videographic documentation of crime scenes. Level 2 technicians routinely perform

forensic photographic techniques, including specialized photography of impression evidence

� Criminalist/Examiner: Includes personnel for whom imaging is a major component of their routine duties. The personnel are not only responsible for the acquisition of

images as a part of their duties but may also be responsible for the analysis of these images

� Photographer/Videographer/Specialist: Includes personnel for whom imaging is the

major component of their routine duties

� Lawyer: Includes prosecutors and defense attorneys

� Judge: Includes personnel who are responsible for the acceptance or rejection of imaging technology-based evidence in court proceedings

� Legal Assistant: Includes personnel who are responsible for preparing materials

that will be offered in court proceedings

� Trainer: Includes personnel who are responsible for providing instruction to others in imaging technology-related areas


Recommended Training Levels

Table 1 provides an assessment of the level of training necessary for each category.

Awareness Skills Knowledge Witness

Testimony Case

Preparation Continuing

Education Specialized

Applications Proficiency

Training

Management High Low Low Low Low Low Low N/A

Command/

Supervision High Low Low Medium Low Low Low N/A

Law Enforcement

Officer Low High Low Low Low Medium Low Low

Crime Scene

Technician Low High Medium High Medium High Medium Medium

Criminalist/

Examiner Low High Medium High High High High High

Photographer/

Videographer/

Specialist Medium High High High High High High High

Lawyer High Low Medium High High Medium Low N/A

Judge High Low Low Low Low Low Low N/A

Legal Assistant Low High Low Medium Medium Medium Low N/A

Trainer * High * * * High * High

* This will depend on the levels of training and the needs of the students.

High - Training and testing are highly recommended for the user group

Medium - Training and testing are recommended for the user group

Low - Training and testing are desirable for the user group

N/A - not applicable

Topical Areas for Focused Training

The following section delineates specific topical areas in which user groups should receive

focused training to effectively fulfill their imaging technology-related duties.

Managers, Commanders/Supervisors, Lawyers, and Judges (awareness and issues training)

� Status of imaging technology

� Legal issues

� Extent of use and who are the users

� Industry and market trends

Version 1.2 2001.12.06


� Description of current technologies

� Strengths and weaknesses of silver imaging

� Strengths and weaknesses of digital imaging

� Strengths and weaknesses of video imaging (analog and digital)

� Current life cycle-cost comparisons and limitations

� Strategic alternatives for the agency

� Determination of imaging needs

� Sequence of equipment/software acquisitions

� Actions to avoid or lessons learned

� References/information sources

Legal Assistants (basic levels of skill for recording images)

� Working knowledge of the basic fundamentals of photography and/or videography

� Working knowledge of the capabilities and limitations of equipment

� Selection and operation of the appropriate cameras (digital, video, or film) and

accessories

� Preparation of court presentations including images

Law Enforcement Officers (first responder)

� Operation of cameras with an understanding of the capabilities and limitations of the equipment assigned as a part of their routine duties

� Selection, framing, and composition of appropriate images

� Procedures for recording quality images in various situations

� Proper collection and preservation of the recording media

� Creation and maintenance of the chain of custody

� Demonstration of competency

� Demonstration of proficiency through testing


Crime Scene Technicians Level 1 (with video or adjustable still cameras)

� Basic levels of skill and knowledge for recording a crime scene

� Various images to take

� Set-ups for each type of image

� Working knowledge of the fundamentals of photography and/or videography

� Proper collection and preservation of the recording media

� Creation and maintenance of the chain of custody

� Working knowledge of the capabilities and limitations of equipment

� Selection and operation of the appropriate cameras (digital, video, or film) and

accessories



Crime Scene Technicians Level 2 (capable of training Level 1 crime scene technicians and law enforcement officers)

� Comprehensive knowledge of and experience in forensic photography techniques,

such as

� Retrieving impression evidence such as fingerprints and/or blood spatter

� Selecting the appropriate film and equipment based on knowledge of the capabilities and limitations of the various aspects of imaging

� Solving difficult non-routine imaging problems

� Awareness of film processing and image processing options; (i.e., the effects of the push process or contrast adjustments)

� Videography techniques (refer to LEVA Guidelines at www.leva.org)

� Knowledge of how to use the most common image processing tools and techniques

� Competency demonstration

� Proficiency demonstration through testing

Version 1.2 2001.12.06


Imaging Specialists

Personnel include photographic specialists, forensic scientists, and forensic video

analysts. These personnel are capable of training law enforcement officers and Level 1 and Level 2 crime scene technicians.

� Working knowledge of how to use the various applicable aspects of the imaging

chain

� Expertise in using techniques applicable to a particular discipline

� Photogrammetry

� Surveillance imaging

� Frequency domain conversion; (i.e., Fast Fourier Transform filtering)

� Alternate light sources and contrast filtering



Trainers

� Classroom techniques

� Development of lesson plans

� Preparation of audio-visual materials

� Development of student exercises

� Selection of text books and reference materials

� Development of course exams

� Development of proficiency exams

� Development of course evaluation processes

� Demonstration of competency in subject matter

� Demonstration of proficiency in subject matter by testing

Issues to Consider when Addressing Training Needs

A number of issues should be considered when addressing an agency's training needs. The following section provides guidance for selecting training providers and addressing continuing education and testimony training needs.


Selecting a Training Provider

Course Instructor Equipment

Is a course outline

provided?

What is the background

and training of the

instructor?

Does the training provider

supply equipment for the

training or must the students

provide their own?

Is the course outline

followed?

Is the training up to

date? How has the

instructor maintained

proficiency in the field?

Is the course equipment

offered by the provider

sufficient to meet the

agency’s course objectives?

Does the course

description include

reference texts and other

materials?

Can the instructor

provide references?

Who provides the facilities,

the agency or the training

provider?

Does the trainer provide

course evaluation forms,

and are past evaluations

available for review?

Is the training affiliated

with professional,

technical, or educational

organizations?

Who provides the audio-

visual equipment?

Is a course manual

provided?

What is the instructor-

to-student ratio?

Are course supplies provided

by the training provider?

Does the provider offer

certificates of completion?

What field expertise

does the instructor have

in the topical area?

Can the course be

customized to meet

agency-specific needs?

Does the class involve

any testing?

Are continuing education

units offered?

Can the training program

travel or must the

students travel to the

instructor?

For whom is the course

intended?

Course objectives

Prerequisites

Current courses

Version 1.2 2001.12.06


Continuing Education

Continuing education can be obtained from training conferences, trade shows, and

specialized courses. This training should address updates and the use of new imaging technologies such as:

� Equipment

� Software

� Imaging techniques applicable to law enforcement

� Scientific techniques beneficial to forensic imaging

Testimony Training

This training should address the use of image-based evidence in court such as:

� Lecture-type presentation relevant to court testimony

� Moot court

� Court monitoring

Version 1.1 2004.03.04


Section 11

DRAFT - Best Practices for Documenting Image

Enhancement

Purpose

The purpose of this document is to describe best practices in the documentation of image enhancement utilized in the criminal justice system. The objective of this

document is to provide laboratory personnel with instruction regarding the level of documentation that is appropriate when performing a variety of enhancement operations on still images, regardless of the tools and devices used to perform the

enhancement. This does not include the creation or conversion from an original source to still images. Note that a fundamental goal of this and other SWGIT documents is to

ensure the successful introduction of forensic imagery as evidence in a court of law. Accurate documentation of image enhancement techniques is a necessary component

to satisfy the legal requirements for the introduction of forensic images as evidence in a court of law.1

The general principles and procedures used are the same regardless of the format or

media in which the images are recorded. Therefore, in this document the word “image” refers to any image recorded on conventional photographic or electromagnetic media.

SWGIT POSITION ON IMAGE ENHANCEMENT

Image enhancement has been used in forensic applications since the early days of photography (1840's). It is an accepted practice in forensic science, regardless of

whether it is performed in a traditional "wet chemistry" darkroom or in a laboratory equipped only with electronic devices such as computers, scanners and/or video capture systems.

IMAGE CATEGORIES

The degree to which procedures used in image enhancement should be documented will

depend upon the intended end use of the image. Furthermore, the nature of such documentation will depend upon the procedures used.

SWGIT recognizes two fundamental end uses for images encountered in the

legal system:

Category 1 Images utilized to demonstrate what the photographer or recording device witnessed but not analyzed by subject matter experts. These can include, but are not limited to,

the following:

1 SWGIT Recommendation and Guidelines for the use of Imaging Technologies in the Criminal Justice System Ver 1.2 Pg. 1

2 Best Practices for Documenting Image Enhancement

� General crime scene or investigative images

� Surveillance images

� Autopsy images

� Documentation of items of evidence in a laboratory

� Arrest photographs ("mug shots")

Category 2 Images utilized for scientific analysis by subject matter experts. These can include, but

are not limited to, the following:

� Latent prints � Questioned documents

� Impression evidence

� Category 1 images to be subjected to analysis

� Patterned evidence

ENHANCEMENT TECHNIQUES

Basic

Basic image enhancement techniques are those used to improve the overall appearance of the image. These techniques can be applied both over an entire image, as well as in localized areas within an image and include only the following:

� Brightness and contrast adjustment, to include dodging and burning;

� Resizing (file interpolation);

� Cropping;

� Positive to negative inversion;

� Image rotation/inversion

� Conversion to grayscale;

� White balance;

� Color balancing/color correction

� Basic image sharpening and blurring (pixel averaging);

2 SWGIT Recommendation and Guidelines for the use of Imaging Technologies in the Criminal Justice System Ver 1.2 Pg. 8

Version 1.1 2004.03.04


� De-interlacing;

� File format conversion Advanced

Advanced image enhancement techniques are techniques applied to images for the purposes of extracting information. These techniques may or may not improve the

overall appearance of the image. The techniques include but are not limited to:

� Frame averaging

� Fourier Analysis (FFT)

� Deblur

� Noise reduction

� Image restoration2

� Color channel selection and subtraction

� Perspective control/geometric correction

� Advanced sharpening tools (such as unsharp mask)

DOCUMENTATION

Category 1 Images Enhancement of Category 1 images need only document their use of such techniques by means of an SOP, which describes their typical enhancement processes. (An

example of a procedure that may be utilized by organizations for this purpose is provided in Appendix A.)

Category 2 Images

The use of advanced enhancement techniques should be documented in every case. The application of basic enhancement techniques can impact the application of and

results from advanced enhancement techniques. Therefore, the application of basic enhancement techniques also requires documentation. The sequence of all

enhancement techniques should be included in the documentation. Documentation of image enhancement steps should be sufficient to permit a

comparably trained individual to understand the steps taken, the techniques used and to extract comparable information from the image. Documentation of every change in

every pixel value is unnecessary and is discouraged because this information adds nothing of value to the analysis.

Exploratory enhancement operations not incorporated into the final image need not be documented. Likewise, test prints/intermediate images resulting from a variety of

techniques that were not incorporated into the final image, should be discarded.


Minimum requirements for documentation include the identification of the software application and/or techniques used along with the settings and parameters. Automated

processes such as the running of user-defined macros require only the documentation of usage as long as the process is defined elsewhere in agency documentation.

Examples of documentation of specific techniques follows:

Brightness and contrast � Contrast adjustment

I printed the image using kodabromide II grade 4 RC paper. The toe region of Q5 was burned in to increase artifact details.

Unsharp mask

� strength, distance, threshold

I used unsharp mask at strength = 100%, with distance = 1.5 pixels, and

threshold of 3 levels. Multiple image averaging

� number of images used, which images were used, individual image weights.

FFT � Specify region of interest parameter, perform FFT, edit spectrum (parameters: spike cut, spike boost, low pass filter, high pass filter), perform IFT (inverse Fourier

Transform)

Noise reduction � type (despeckle, Gaussian blur, etc.)

I reduced noise in the image by applying an IIR Gaussian blur.

Color channel selection and removal

� channel

I removed the Red channel by deleting it. Perspective control/geometric correction

� scale, rotation (degrees), perspective, skew

I rotated the image 90 degrees clockwise. User-defined Macro

� macro name

In Adobe Photoshop Ver. 7.0 I used Action “Video Process 1” (Defined in

agency documentation)

These examples are only intended as a representation of the level of documentation

that is appropriate for category 2 images. Category 2 images are used for analysis purposes and any enhancements must be completely documented. Enhancements

Version 1.1 2004.03.04


purposes and any enhancements must be completely documented. Enhancements to category 1 images need only be documented through agency standard operating

procedures and are limited to basic enhancement techniques. Following these recommendations will assist in fulfilling the requirements for the admissibility of images in a court of law.


Appendix “A”

In the following example the requirement to document all enhancements to category 2 images is met by the use of the “Enhanced Image History” tool found in the software

package used by this agency.

FLORIDA DEPARTMENT OF LAW ENFORCEMENT

FORENSIC SCIENCE QUALITY MANUAL

STANDARD OPERATING PROCEDURES DIGITAL IMAGING

TITLE

Latent Print Image Processing

DATE OF APPROVAL _______________________________ SIGNATURE OF REVIEWER

___________________________

________________________________ Technical Leader Director of Forensic Services

PURPOSE:

To establish a list of actions for the enhancement of latent print images as requested by Latent Print Analysts.

PROCEDURES:

Latent print image processing (enhancement) will be done through the “More Hits” program. (“More Hits” is the image tracking software currently approved for use by FDLE in latent print capture/processing.)

Log onto the “More Hits” program.

Select the case containing the images that need to be processed.

On the Menu Bar, click Image, Enhance. The program will make a copy (Working Image) of the original image and import it into the image processing program

(PhotoShop) along with the “Enhanced Image History”.

Process the Working Image using the tools provided in the image enhancement program.

All processes applied to the Working Image will be recorded using the “Enhanced Image

History” tool.

Version 1.1 2004.03.04


Processing techniques approved for use on Working Images are those that have direct counterparts in traditional darkrooms. These include brightness and contrast

adjustment, dodging and burning, color balancing. These tools include Brightness/Contrast, Levels, Curves, Color Balance, Hue/Saturation and Invert. Additionally, using Mode, channels and FFT filters is acceptable.

Tools prohibited for use on Working Images are those that add or delete content from

the image. These include, but are not limited to, Rubber Stamp, Airbrush, Paintbrush, Paint Bucket, Eraser and Blur.

After the Working Image has been processed and the processes have been recorded, the image processing program is exited and the changes to the image are saved. The

processed Working Image is imported back into the “More Hits” program. At this point, the operator may continue processing additional images, exporting a processed image for printing or

exiting the program.

SAFETY CONSIDERATIONS: None

LIMITATIONS: Based upon existing equipment and technology QUALITY CONTROL: Perform appropriate equipment maintenance to insure quality of

performance and that they are operating in their proper capacity

LITERATURE REFERENCES: Adobe Photoshop Users Manual

MORE HITS User Manual

Version 1.2 2004.07.01

Section 12

DRAFT-Best Practices for Practitioners of Forensic Image Analysis

OBJECTIVE The objective of this document is to provide laboratory personnel with guidance regarding practices appropriate when performing a variety of analytic tasks involving images, regardless of the knowledge domain that is the subject of analysis.

SWGIT POSITION ON FORENSIC IMAGE ANALYSIS Forensic image analysis is a forensic science. It has been practiced since the early days of photography (1840's). In addition to being an accepted scientific practice in the forensic community, image analysis is also recognized in other disciplines including medicine, intelligence, geology, astronomy, agriculture, and others.

INTRODUCTION Forensic Image Analysis is the application of image science and domain expertise to interpret the content of an image and/or the image itself in legal matters. This can involve several different tasks. These tasks fall into three categories: Interpretation, Examination, and Technical Preparation. These tasks are commonly performed in the following areas: Photogrammetry, Photographic Comparison, Content Analysis, and Image Authentication. These tasks are described below. The general principles and procedures used are the same regardless of the format or media in which the images are recorded. Therefore, in this document the word “image” refers to any image recorded on any media (e.g., conventional photographic, electronic, magnetic, or optical media, etc.).

FORENSIC IMAGE ANALYSIS – GENERAL TASKS

Interpretation Interpretation, as used here, is the application of specific subject matter expertise to draw conclusions about subjects or objects depicted in images. Examples include a podiatrist drawing conclusions about foot shape from an image, a shoeprint expert drawing conclusions about the provenance of a shoe, or a military expert drawing conclusions about force distribution from remote sensing data.

Examination Examination is the application of image science expertise to the extraction of information from images, the characterization of image features, and the interpretation of image structure. Examples include watermark detection, steganalysis, and image alteration evaluation, as well as the development of case-specific image exploration strategies. Image enhancement, image restoration, and other image processing activities intended to improve the visual appearance of features in an image are examination tasks.

SWGIT Guidelines for the Forensic Image Practitioner 1

Technical Preparation Technical preparation is the performance of tasks such as preparation of evidence or images for examination, interpretation, or output. Note that there is a wide gamut of technical decision making within the various responsibilities covered by technical preparation actions. Some responsibilities may involve minimal technical decision making, such as feeding paper into a preset sheet fed scanner that has been previously calibrated. Some responsibilities may involve a great deal of technical decision making, such as determining appropriate color balance, sampling during acquisition, or output resolution. Note: Interpretation, Examination, and Technical Preparation are tasks, not job descriptions or roles. An individual may perform part of one task or a combination of multiple tasks within the organizational structure of any given activity. Each of these tasks requires its own training and qualification.

FORENSIC IMAGE ANALYSIS – SPECIFIC AREAS OF ANALYSIS

Photogrammetry “Photogrammetry is the art, science, and technology of obtaining reliable information about physical objects and the environment through the processes of recording, measuring, and interpreting photographic images and patterns of electromagnetic radiant energy and other phenomena.” [from “The Manual of Photogrammetry, 4th Edition, 1980, ASPRS]. In forensic applications, photogrammetry (sometimes called “mensuration”) most commonly is used to extract dimensional information from images, such as the height of subjects depicted in surveillance images and accident scene reconstruction. Other forensic photogrammetric applications include visibility and spectral analyses. Figure 1 depicts an example of a photogrammetric analysis conducted to determine the height of a subject pictured in a bank robbery surveillance photograph.

Figure 1.

2 Best Practices for Imaging Practitioners of Forensic Image Analysis

Version 1.2 2004.07.01

Photographic Comparisons Photographic comparison is assessment of the correspondence between features in images and known objects for the purpose of rendering an expert opinion regarding identification or elimination (as opposed to a demonstrative exhibit). Examples of photographic comparisons include, but are not limited to:

A facial comparison between an unknown subject depicted in a surveillance image with an identified suspect; The comparison of objects such as vehicles depicted in surveillance images with

those recovered in an investigation;

The comparison of a questioned image with a known camera to determine if the image was captured using that camera.

Photographic comparisons are frequently referred to as “side-by-side” comparisons since they usually involve a comparison of class and individualizing characteristics in imagery. The scientific processes involved in photographic comparisons are comparable to those used in other forensic disciplines such as fingerprint analysis. Two commonly accepted scientific protocols that may be applied to photographic comparisons are ACE-V (Analysis, Comparison, Evaluation – Verification) and statistical analysis. Figure 2 depicts demonstrative exhibits from a facial comparison exam, in which ACE-V was used to individualize the subject as the same person in both images.

Figure 2.

SWGIT Guidelines for the Forensic Image Practitioner 3

Figure 3.

Figure 3 depicts a demonstrative exhibit from a clothing comparison examination, in which ACE-V was used to individualize the camouflage jacket as the same one in both images.

Content Analysis Content analysis is the drawing of conclusions about an image. Targets for content analysis include, but are not limited to:

the subjects/objects within an image; the conditions under which, or the process by which, the image was captured or

created;

the physical aspects of the scene (e.g., lighting or composition); and/or

the provenance of the image.

Examples include vehicle license plate number identification, patterned injury analysis, correlation of injuries inflicted in an image sequence with autopsy results, determination of the presence of computer-generated imagery in an alleged “snuff” film, and determination of the type of camera used to record a specific image.

Image Authentication Image Authentication is verification that the information content of the analyzed material is an accurate rendition of the original data by some defined criteria. These criteria usually involve the interpretability of the data, and not simple format changes that do not alter the meaning or content of the data. Examples include:

Determining the degradation of a transmitted image; Determining whether a video is an original recording or an edited version;

Evaluating the degree of information loss in an image saved using lossy

compression.

4 Best Practices for Imaging Practitioners of Forensic Image Analysis

Version 1.4 2004.12.29

Determining whether an image contains feature-based modifications such as the addition or removal of elements in the image (e.g., adding bruises to a face).

BEST PRACTICES The following are guidelines that describe the SWGIT recommended best practices for the performance of forensic image analysis.

Evidence Management Agencies should have documented procedures for the handling, transportation, and storage of evidence. Agencies should have chain of custody procedures in place and should follow these procedures.

Quality Control and Quality Assurance Quality control and quality assurance policies and procedures should be implemented and documented. Technical and Administrative peer reviews are integral components of quality control.

Security There should be procedures in place to maintain the security of the working data, all notes, and other such analysis-related materials to provide the level of security and privacy needed by the organization. For example, archived case-related materials should be stored in a manner that limits access. The degree of access will be agency-specific.

Infrastructure Agencies should have sufficient space, equipment and facilities to adequately support the required quality and volume of work.

Work Management Because forensic image analysis is a labor-intensive process, an upper limit on caseload should be established for every category of tasks.

Documentation Most image analysis techniques are based in accepted scientific methods. The practitioner should have available documentation that describes and justifies the use of any method involved in the analysis. Such documentation can include peer-reviewed journal articles, scientific conference proceedings, reference books, internal white papers, or the results of empirical studies. The application of analytic techniques in a given case should be recorded to the degree that a similarly trained professional could obtain similar results. Agencies should establish standards for information included in, and the format for, reporting results.

Training, Competency, and Proficiency Analysts should have certification in their knowledge domain and associated forensic discipline, when such certification is appropriate and available. Note, however, that the

SWGIT Guidelines for the Forensic Image Analysis Practitioner 5

mere existence of a certification program does not imply that it is necessary, sufficient, or appropriate. Analysts should demonstrate competency in their discipline prior to being assigned unsupervised case work responsibilities. Agencies should document competency requirements. Analysts should demonstrate proficiency and maintain continuing education activities. Agencies should document proficiency and continuing education requirements.

Competency Requirements for Individuals Conducting Forensic Image Analysis The practitioner should demonstrate:

an understanding of the scope of work and how it will be applied in the forensic environment;

subject matter knowledge and competence;

a working knowledge of the potential image processing and evaluation

techniques;

a working knowledge of applications and tools utilized in the specific laboratory;

a working knowledge of SWGIT guidelines for capturing, storing, and processing of imagery, including issues relating to topics such as data integrity and compression artifacts;

an understanding of legal precedent for the use of specific image processing

techniques;

knowledge of the techniques necessary to document the conclusions.

Standard Operating Procedures (SOPs) There should be Standard Operating Procedures (SOPs) for the tasks being performed. These SOPs should reflect the work flow and be general enough to permit flexibility for the required tasks.

Work Flow The following describes a generalized sequence of actions involved in the analysis of an image and recommendations for their performance. The exact sequence will be agency specific.

(1) Review of request for analysis. a. The agency must confirm that it performs the requested analysis. b. The agency must confirm that the items received from the requestor are

the items needed to perform the requested analysis.

c. The agency must confirm that it has the necessary equipment, materials, and resources needed to conduct the requested analysis.

6 Best Practices for Practitioners of Forensic Image Analysis

Version 1.4 2004.12.29

d. The agency must assign the analysis request to the appropriate personnel.

(2) Acquisition of imagery.

This is the implementation of the acquisition strategy determined in the initial assessment. It produces the image for the steps that follow. Often, analysis or examination may be performed on objects directly or on analog images without the need for digitization. The primary or original image should be archived in a manner that permits verification. The image acquisition step is where the integrity of the primary or original data is initially established. Most often, subsequent steps are performed utilizing working copies, but in all cases, the integrity of the primary or original image(s) must be maintained.

a. If possible, the original or primary image, or a bit-for-bit duplicate,

should be available for analysis. b. Triage imagery

i. The practitioner must determine if the submitted material is suitable for analysis.

ii. The practitioner must determine if all of the submitted material,

or only a subset of the material, is to be subjected to analysis.

(3) Production of Working Copies. Produce working copies of images to be subjected to analysis. This may

require digitization from negatives, prints, or conversion from other media.

(4) Processing of Images to be Analyzed. (Note: Guidance relating to forensic image processing [FIP] and case-specific

documentation requirements for FIP can be found in SWGIT IP document [January 2003] and the SWGIT Forensic Photography Best Practices Image Enhancement document)

a. Design an image processing strategy. This is the application of domain knowledge to choose which processes to apply to the image to extract the information necessary for drawing a conclusion. The strategy should be justifiable. No single processing strategy is appropriate for all cases. This should be reflected in the organizational SOPs. Exploratory strategies that are not incorporated into the final work flow pathway need not be documented.

b. Identify the appropriate tools to implement the strategy. There should

be some references/documentation that the selected tools are capable of implementing the strategy.

c. Implement the designed image processing strategy.

d. Assess results. Determine that the image processing strategy yielded

results suitable for analysis.


(5) Analyze processed data.

a. Determine if criteria necessary for reaching a conclusion are present in the processed image.

i. Specific criteria for reaching a conclusion should be identified and

documented.

ii. In some cases, the criteria will reflect the subjective experience of the practitioner. Such conclusions should be confirmed through appropriate peer review policies for individual cases.

b. Reach conclusion.

(6) Report Conclusions. a. Some conclusions can be based on statistical criteria, while other

conclusions are based on subjective criteria. Conclusions derived from photogrammetric analyses can often be reported in terms of statistical criteria. In contrast, many conclusions derived from image content analyses are based on subjective criteria. The basis for, and uncertainty of, any conclusion should be reflected in the reporting.

b. When a statistical basis for a conclusion can be made, the conclusion

should be quantitatively reported. It may be possible to provide bounds on probabilities based on incomplete knowledge. See Appendix A.

c. When statistical criteria do not exist, the conclusion should be reported

in terms of the kind of features discerned. One way of doing this is to use a graded scale. An example of such a scale is provided in Appendix B.

d. The report format and contents should follow agency standards.

Work Flow Examples

Photogrammetric Analysis Example A local police agency asks the state crime lab to determine the height of the individual depicted robbing the convenience store in a surveillance video tape. The police have two suspects of different heights and would like the crime lab to determine if either can be excluded on this basis. Following the workflow delineated above, the agency proceeds:

1 The agency reviews the request and:

a. determines that they perform this type of analysis,

b. determines that the items received from the requestor are the items needed to perform the requested analysis,


Version 1.4 2004.12.29

c. determines that they have the necessary equipment, materials, and resources needed to conduct the requested analysis, and

d. they assign the analysis request to an analyst.

2 The analyst acquires the necessary imagery.

a. The analyst observes that the videotape has no markings that would indicate that it is a copy, then verifies that it is an original using available video test equipment.

b. The practitioner reviews the video sequence of interest and locates images suitable for photogrammetric analysis.

3 The analyst digitizes still images from the analog video sequence for use in the

analysis as working copies.

4 Standard image processing techniques such as brightness and contrast adjustments and deinterlacing are applied to the working images.

5 The analyst imports the images into a photogrammetric application and

conducts an analysis. This analysis results in a calculated value for the robber’s height, as well as a determination of the accuracy and precision of this result. The analyst compares these results with the reported heights of the two suspects and eliminates one of the suspects on this basis.

6 The analyst writes the report. Per the crime lab’s SOPs, the report includes a

review of the materials received, the request, the methods used, the results obtained, an estimate of accuracy and precision, the basis for the conclusion, and the conclusion.

Photographic Comparison Example An FBI field office investigating a report of child abuse recovers a floppy disk containing digital image files that appear to depict the suspect’s left hand upon a victim. A second floppy disk is received containing digital image files of a known suspect’s left hand. An FBI image analysis unit is requested to perform a photographic comparison of the questioned and known hands to determine if the hands belong to the same individual.

Following the work flow described above, the unit proceeds:

1 The agency reviews the request and: a. determines that they perform this type of analysis, b. determines that the items received from the requestor are the items needed to perform the requested analysis,


d. they assign the analysis request to an analyst.


2 The analyst acquires the necessary imagery.

a. The analyst calls the investigating agency and determines that copies of the original images have been received. The authentication was performed by the investigating agency. b. The practitioner reviews the imagery and selects several images for further analysis.

3 The analyst makes copies of the selected imagery for use as working copies,

and safely stores the received data.

4 Image processing techniques such as brightness and contrast adjustments, unsharp masking, and multi-pixel averaging are performed. The use of these techniques are documented per the units SOP.

5 The resulting images are analyzed and it is determined that compression

artifacts present in the questioned images prevent unambiguous identification of individualizing features on the hand. The class characteristics of the questioned and known hands, however, are observed to be similar. Therefore, the analyst concludes that the suspect can neither be identified nor eliminated from the imagery.

6 The analyst writes the report. Per the crime lab’s SOPs, the report includes a

review of the materials received, the request, the methods used, the results obtained, the basis for the conclusion, and the conclusion.

Content Analysis Example A four-year-old child is admitted to the hospital, complaining of fever. Emergency room physicians note a confluent red rash over the victim’s trunk and groin. The child begins having seizures, stops breathing, and dies. Resuscitation efforts fail. The local physician signs the death certificate as “death due to scarlet fever.” The coroner is not informed of the death, and the body is cremated. Three weeks after cremation, a family member makes the accusation that the child had been dipped in boiling water. The ER physician had taken digital snapshots of the rash as a teaching tool. The county medical examiner’s office is asked to evaluate the imagery to determine if the injuries are consistent with scarlatina or child abuse. Following the work flow described above, the medical examiner’s office proceeds:

1 The agency reviews the request and: a. determines that they perform this type of analysis, b. determines that the items received from the requestor are the items needed to perform the requested analysis,


d. they assign the analysis request to a medical examiner (ME).


Version 1.4 2004.12.29

2 The ME acquires the necessary imagery.

a. The ME calls the hospital and subpoenas the child’s records. b. The ME confirms that the imagery is a copy of the digital snapshots taken by the ER doctor.

c. The ME reviews the documents and imagery and selects several images for further analysis.

3 The ME makes working copies of the selected imagery, and safely stores the received data.

4 No image processing is required.

5 The selected images are analyzed and it is determined that the pattern of injury

on the body, the location on the body, and the texture of the rash, is incompatible with immersion in boiling water. Examination of the medical records reveals a positive blood culture for Streptococcus pyogenes. In addition, a rapid test for influenza A was performed and was positive. Therefore, the ME concludes that the skin lesion was due to scarlatina resulting from a S. pyogenes superinfection secondary to influenza A.

6 The ME writes the report. Per the Medical Examiner’s Office’s SOPs, the reasoning

behind the conclusions and the results are detailed. Because all information necessary to reproduce the conclusion is contained within the report, upon the completion of peer and administrative review, all working notes are shredded per the agency SOP.


APPENDIX A

Reporting Conclusions through Quantitative Means (Example)

Classic photogrammetric evaluation is amenable to estimation of error, either through the propagation of error involved in the calculations or in comparison with fiducials that may be present in an image. The reader is referred to standard photogrammetric and numerical methods texts for the former. In many images that require measurement, there are objects of known dimension. These may be used to provide estimates of error. Both common kinds of error (imprecision and bias) should be estimated if possible, and if not possible, the limitations of the method should be mentioned in the final report.

Example: Evaluation of hostage photograph. A government agency has obtained a photograph of a middle-aged male hostage. They wish an estimate of the time since capture based on the assumption that the man has not been allowed to shave. The analyst is instructed to measure the hairs on the chin of the hostage and estimate the time since last shave. The hostage photograph is taken with the hostage holding a newspaper below his chin, and the date is estimated to be in mid-May. In addition, the victim is wearing a known brand shirt, with buttons of minimal manufactured tolerance. The button diameter is 12mm (+/- 0.0001 mm).

Photogrammetric measurement of 6 buttons reveals an average measured diameter of 12.01 mm (+/- 0.02 mm). Measurement of 100 hairs on the chin reveals an average length of 3.2 mm (+/- 0.3mm) for pigmented hairs and 7.2 mm (+/- 0.5 mm) for nonpigmented hairs.

The photogrammetric error is thus of an order of magnitude less than the error of the hair, and can be discounted. The published average growth rate for beard hair is 0.47mm/day for pigmented hair (+/- 0.2mm) and 1.12 mm/day for white hair. The May date allows negligible adjustment for seasonal hair growth variation (which may be up to 60%). White hair growth data is discarded because of great interpersonal variation.

The estimate of beard growth is thus 3.2/0.47 = 6.8 days, with an estimated

error of sqrt[(0.3/3.2)*(0.3/3.2) + (0.2/.42)*(0.2/.42)]*6.8 or 3.3 days.

The estimate is thus that the hostage had been kept for 6.8 +/- 3.3 days, ignoring the (sizeable) seasonal variation and (possibly sizeable) nutritional effects. Both the error and the ignored sources of error are noted in the final report.


Version 1.4 2004.12.29

APPENDIX B

Reporting Conclusions Through the Use of a Graded Scale (Example and Commentary)

When a statistical basis for the conclusion can be made, the conclusion should be reported in terms of probability. When statistical criteria do not exist, the conclusion should be reported in terms of the kind of features discerned and their correspondence or disagreement. One way of doing this is through the use of a graded scale such as the following:

• Grade 0: Exclusion. • Grade 1: Correspondence of class characteristics only. • Grade 2: Correspondence of class characteristics and pseudorandom

characteristics for which the underlying probability distribution is unknown.

• Grade 3: Correspondence of class characteristics and acquired/random characteristics which can be considered unique within a selected population.

It may be possible to provide bounds on probabilities based on incomplete

knowledge. If the examiner decides to provide such a bound, then a statement of probabilities can be made as commentary, with explicit description of the underlying assumptions. For example, consider a piece of clothing with a given fabric pattern. An estimate of a certain percentage could be made that the cloth has a given orientation for one panel and another percentage for another panel. If the assumption is made (and stated), or if investigation of the manufacturing process allows determination that the orientations are independent, then it is possible to calculate a total probability by multiplying the individual probabilities. Thus, if panel A is at most 40% likely to have a given orientation, and panel B is at most 40% likely to have a given orientation, then an upper bound of 16% of the clothing thus made will have that particular combination of panel orientations. For the most part, however, these kinds of data are not available to investigators, and the limit of examination will be a grade-based conclusion.


April 27, 2004

Dear Colleague,

A number of law enforcement officials in North America

have approached the Scientific Working Group on Imaging

Technology (SWGIT) requesting guidance in developing

policies and procedures to acquire and protect their

digital image evidence. Many express concern regarding

potential challenges to the integrity of digital images.

With those individuals in mind, the SWGIT is pleased to

present the attached document “Digital Imaging Procedure,

Version 1.0” to the forensic community at large.

This document was published by the United Kingdom’s

Police Scientific Development Branch (PSDB), which has

agreed to let us distribute it through the Forensic Science

Communications. We are doing so because this document

addresses the issues of digital image acquisition and

integrity in a straightforward manner that is consistent

with the guidelines and recommendations of SWGIT.

SWGIT strongly encourages agencies to incorporate the

recommendations provided in this document within their own

policies and procedures as they see fit. In doing so,

agencies will be taking an important step to ensure the

integrity of their digital image evidence.

Among the most critical fundamental ideas presented in

this document is the concept of a “Master Copy”, which

serves as the digital equivalent of an original film

negative or video tape. A “Master Copy” represents either

a bit-for-bit duplicate of original digital files or as a

digital copy of an analog recording that has been written

to removable media, such as a compact disc or DVD-R. Once

such a “Master Copy” has been generated, it can be handled

using the same policies and procedures an agency would use

to protect and preserve the integrity of an original film

negative or video tape.

As this “Digital Imaging Procedure, Version 1.0”

points out, although it is commonly accepted that a

credible manipulation of digital image files can be

accomplished relatively easily, it is very difficult to

conceal manipulation when the manipulated file is compared

to the “Master” file. Thus, creation of a “Master Copy”

represents the most critical step in any procedure

involving digital image files.

Another important concept discussed within this

document is the fact that imaging devices – whether they

are film, video, or digital still cameras - do not

duplicate (or clone) reality, but merely generate a visual

representation of a subject. The degree to which an image

represents a “life-like” simulation of reality will be a

function of many factors, including such things as the type

of camera used, the processing applied to the image, and

the means by which the image is displayed. Agencies and

personnel utilizing images should be cognizant of the

capabilities and limitations of different technologies.

Furthermore, agencies must develop policies and procedures

and utilize technology that will enable them to generate

images of sufficient quality to accomplish their given

mission.

SWGIT notes that some of the guidance provided in this

document may only apply to agencies operating within the

United Kingdom. Agencies planning on implementing the

guidelines within North America or elsewhere should take

care to ensure that they meet statutory requirements within

their jurisdiction.

The SWGIT will continue developing guidelines for the

use of imaging technology in the criminal justice system.

We will also continue to reach out to our international

partners to identify similar documents and guidelines that

will be of benefit to our local community. We hope you

find this document of assistance in your work.

Sincerely,

Richard W. Vorder Bruegge

SWGIT Chair

SWGDE/SWGIT Recommended Guidelines for Developing Standard Operating Procedures Version: 1.0 (November 15, 2004)

This document includes a cover page with the SWGDE/SWGIT disclaimer. Page 1 of 8

Recommended Guidelines for Developing

Standard Operating Procedures

Disclaimer: As a condition to the use of this document and the information contained therein, the SWGDE/SWGIT request notification by e-mail before or contemporaneous to the introduction of this document, or any portion thereof, as a marked exhibit offered for or moved into evidence in any judicial, administrative, legislative or adjudicatory hearing or other proceeding (including discovery proceedings) in the United States or any Foreign country. Such notification shall include: 1) The formal name of the proceeding, including docket number or similar identifier; 2) the name and location of the body conducting the hearing or proceeding; 3) subsequent to the use of this document in a formal proceeding please notify SWGDE/SWGIT as to its use and outcome; 4) the name, mailing address (if available) and contact information of the party offering or moving the document into evidence. Notifications should be sent to: [email protected]. Redistribution Policy: SWGDE/SWGIT grant permission for redistribution and use of all publicly posted documents created by SWGDE/SWGIT provided that the following conditions are met: 1. Redistributions of documents, or parts of documents, must retain the

SWGDE/SWGIT cover page containing the disclaimer. 2. Neither the name of SWGDE/SWGIT, nor the names of its contributors, may be

used to endorse or promote products derived from its documents. 3. Any reference or quote from a SWGDE/SWGIT document must include the version

number (or create date) of the document and mention if the document is in a draft status.

SScciieennttiiffiicc WWoorrkkiinngg GGrroouuppss oonn DDiiggiittaall EEvviiddeennccee aanndd IImmaaggiinngg TTeecchhnnoollooggyy



Recommended Guidelines for Developing Standard Operating Procedures

Introduction: Standard Operating Procedures (SOPs) are agency unique documents describing the methods and procedures to be followed in performing routine operations. SOPs are essential to improve the quality and to implement uniform processes for conducting digital & multimedia evidence forensic tasks in a precise, accurate manner. SOPs should be task-based and written for each procedure conducted. They should be reviewed at least annually. The previously approved versions of an SOP should be retained for reference. Scope: SOPs should conform to agency-specific policies. Such policies may address document format, workflow, approval process, and tasks performed. SOPs may be stored separately, in one large collected manual, or organized by functional unit. For instance, a single manual may be more convenient, but having separate SOP documents may be more amenable to the discovery process. SOPs should contain all information necessary to perform the task being described. Individual agency needs and/or processes will dictate what information is necessary. General Guidelines: SOPs may include but are not limited to: The name of the SOP, effective date and/or other version control. The purpose and scope of the SOP. Definitions and abbreviations that are not commonly used or have a special

connotation in the SOP. The source of these definitions should be cited. A list of equipment, materials and standards/controls.

Note: Since equipment and material lists are frequently updated, it may be

beneficial to create a separate listing of this equipment. This will allow for a document that can be updated independent of the SOP.

Equipment calibration and similar preparatory steps, if applicable. Any known limitations of the equipment, software or procedure. A list of steps used in performing the task, including appropriate parameters or

options to be used. Appropriate references. This may include equipment manuals, other published

procedures, journal references, etc. Any additional information/materials the examiner needs to be aware of that

are not already included in the sections above, such as safety issues or



operational precautions. Authorization and approval information.

Sample SOPs are provided for your reference. These are examples only and are not meant to be boilerplate.



S-A-M-P-L-E

Sample Standard Operating Procedure Wiping Media Version: Draft 1.0 (08/2003) Version: Revised Draft 1.1 (02/2004) Version: Revised Draft 2.0 (4/2004)

Note: The sample standard operating procedures are given as an example only and are not meant to be used without revision.

Introduction/Scope: This procedure applies to wiping media for hard disk drives and other digital media. This procedure applies to computer forensic examiners in this agency. Purpose: To completely erase, by overwriting, all data on digital media including both physical and logical structures. Equipment: Χ Media to be wiped Χ Examination station Χ ABC software wiping utility (current or appropriate version) Definitions: Wiping - To erase completely by overwriting all data on digital media including both physical and logical structures, Calibration: None Limitations: This procedure may not apply to all forms of media, such as tapes or diskettes. Procedure:

1. Ensure the examination station is powered off.

2. Attach media to be wiped to examination station.

3. Power on the examination station.

4. Start wiping process utilizing appropriate software commands.



S-A-M-P-L-E

5. When process is complete, verify the media has been wiped.

6. Power off examination station.

7. Remove the media.

References: ABC user manual for software wiping utility. Notes: Examiners should double check media before wiping to ensure no irreplaceable data will be lost. History:

Revision

Date

Section

Change

1.1

01/05/2004

Notes

Spelling correction

This standard operating procedure has been approved for use. Jane Doe Approving Authority Date



S-A-M-P-L-E

Sample Standard Operating Procedure Video Processing

Note: The sample standard operating procedures are given as an example only and are not meant to be used without revision.

1. Do a visual inspection of the tape and cassette housing to

a. Ensure housing is intact

b. Inspect tape for damage (e.g., twisting, separation)

c. If damage is found, take corrective action and document.

2. Enable any record-protection device (e.g., punch-out tab, slide record tab, remove record button).

3. Determine if the submitted tape is an original or a copy. If it is an original,

proceed to Step 4. If it is a copy, contact the submitter and request that original tape be submitted, and terminate examination of the copy. If the copy is the best available, proceed with the examination.

4. Determine the make, model, and settings of the device used to record the

submitted video, if possible. These settings may include the recording format and speed.

5. Select the appropriate playback device(s) to achieve optimal signal quality.

6. Using the selected devices and settings, review the submitted video to locate the

pertinent segment(s).

7. Determine the appropriate playback speed for processing.

8. A time-base corrector may be used to stabilize the signal for playback and permit adjustment of video, chroma, pedestal levels, or other signals.

9. At the examiner’s discretion, a working copy of the pertinent segment may be

generated using an available analog or digital device.

10. The images may be enhanced using a number of processing operations that may include but are not limited to histogram equalization, multiframe averaging, contrast and levels adjustments, and sharpening.



S-A-M-P-L-E

11. Once enhanced, the final images are output to appropriate media. This standard operating procedure has been approved for use. Jane Doe Approving Authority Date



History

SWGDE/SWGIT Recommended Guidelines for Developing Standard Operating Procedures

Revision Issue Date Section

History

1.0 11/15/04 All Original Release

90 Wn. App. 100, STATE v. HAYDEN [No. 38162-8-1. Division One. February 17, 1998.]

THE STATE OF WASHINGTON, Respondent, v. ERIC H. HAYDEN, Appellant.

[1] Evidence - Opinion Evidence - Expert Testimony - Scientific Evidence - Novel Evidence - Acceptance in Scientific Community - Frye Standard. Evidence of a novel scientific theory or method of proof may be admitted in a criminal trial if the theory or method of proof is generally accepted in the relevant scientific community. This rule is popularly known as the Frye standard for admissibility Frye v. United States, 293 F. 1013 (D.C. Cir. 1923).

[2] Evidence - Opinion Evidence - Expert Testimony - Scientific Evidence - Conventional Evidence - Frye Standard - Applicability. Evidence of a scientific theory or method of proof that is not new or unusual may be admitted in a criminal trial without first determining that the theory or method of proof is generally accepted in the relevant scientific community.

[3] Evidence - Opinion Evidence - Expert Testimony - Scientific Evidence - Full Acceptance in Scientific Community - Effect. The full acceptance of a scientific theory or method of proof in the relevant scientific community obviates the need for a Frye hearing before evidence of the theory or method of proof may be admitted in a criminal trial.

[4] Evidence - Opinion Evidence - Expert Testimony - Scientific Evidence - Acceptance in Scientific Community - Review - Standard of Review. A trial court's determination that a scientific theory or principle has achieved general acceptance in the relevant scientific community is reviewed de novo.

[5] Evidence - Opinion Evidence - Expert Testimony - Scientific Evidence - Acceptance in Scientific Community - Review - Sources of Information. In deciding whether a scientific theory or method of proof is generally accepted in the relevant scientific community, an appellate court examines the record, the available literature, and cases from other jurisdictions.

[6] Evidence - Opinion Evidence - Expert Testimony - Scientific Evidence - Acceptance in Scientific Community - Determination. A scientific theory or method of proof is generally accepted in the relevant scientific community if there are no significant disputes among qualified experts as to the validity of the theory or method of proof.

[7] Evidence - Opinion Evidence - Expert Testimony - Scientific Evidence - Enhanced Digital Imaging - Bloody Handprint - Frye Standard - General Acceptance. The process of enhanced digital imaging performed by qualified experts using appropriate software to establish a match of a bloody handprint on a piece of fabric is generally accepted in the relevant scientific community.

Nature of Action: Prosecution for first degree felony murder. Superior Court: The Superior Court for King County, No. 95-1-04024-8, Marilyn R. Sellers, J., on February 16, 1996, entered a judgment on a verdict of guilty.

Court of Appeals: Holding that an enhanced digital image of a bloody handprint found on a bed sheet at the murder scene was properly admitted at trial, the court affirms the judgment.

Kelly V. Curtin of Nielsen, Broman & Associates, P.L.L.C., for appellant.

Norm Maleng, Prosecuting Attorney, and Tod J. Bergstrom, Deputy, for respondent.

KENNEDY, A.C.J. - Eric H. Hayden appeals his conviction of felony murder in the first degree, contending that the trial court erred in admitting enhanced-fingerprint evidence after conducting a Frye«1» hearing and by ordering him to obtain a mental health evaluation and undergo treatment as a condition of his community placement following the completion of his confinement.«2» Finding no error, we affirm.

FACTS Dawn Fehring, a 27-year-old student, was found dead on the floor of her Kirkland apartment on Sunday, May 14, 1995. She was discovered nude near the foot of her bed with her top bed sheet and T-shirt wrapped around her head and neck. Bloodstains were found on the carpet near her body and bloody handprints were visible on the fitted bed sheet covering the mattress. An autopsy revealed that Fehring died from asphyxiation sometime the previous Friday evening and that the source of the blood was two tears on her hymen.

During the ensuing investigation, police interviewed occupants of the other apartments in the building, one of whom was appellant Eric Hayden. Hayden became a suspect when he was unable to account for his whereabouts on the night of the murder and seemed nervous during a police interview. He told police that he had been drinking with friends on Friday evening but was unable to identify the friends. He told his girl friend that he was too drunk that evening to remember where he had been.

The Kirkland Police Department took the fitted bed sheet to Daniel Holshue, a King County latent print examiner. Holshue cut out the five areas of the bed sheet that contained the most blood and prints. He then treated the pieces of sheet with a dye stain called amido black that reacted with the protein in the blood, turning the sheet navy blue. Next, he rinsed the pieces of sheet in pure methanol to lighten the background, leaving only the protein stains dark blue.

Finally, he dipped the pieces in distilled water to set the prints. Still, after these chemical processes were completed, the contrast between the latent prints and the pieces of bed sheet was too subtle for Holshue to identify the minimum of eight points of comparison required to make a positive identification.

Holshue took the pieces of sheet to Erik Berg, an expert in enhanced digital imaging at the Tacoma Police Department, for computer enhancement. Berg took computer photographs, or digital images, of the pieces of sheet and then utilized computer software to filter out background patterns and colors to enhance the images so that the prints could be viewed without the background patterns and colors. Using the enhanced photographs of the latent prints, Holshue found twelve points of comparison on one of the fingerprints and more than forty on one of the palm prints. Thus, he concluded that the prints on the bed sheet belonged to Eric Hayden.

«1» Frye v. United. States, 293 F. 1013, 34 A.L.R. 145 (D.C. Cir. 1923).

«2» We treat this second issue in the unpublished portion of this opinion.

On June 5, 1995, the State charged Hayden by information with one count of felony murder in the first degree in violation of RCW 9A.32.030(1)(c). Specifically, it alleged that Hayden committed the crime of rape against Fehring, causing her death in the course of, in furtherance, and in immediate flight from that crime. After an eight-day trial, a jury found Hayden guilty. The court sentenced Hayden within the standard range and ordered him to obtain a written mental health evaluation and complete all treatment recommendations as a condition of his community placement following the completion of his prison sentence. Hayden appeals.

ANALYSIS [1-3] Our Supreme Court recently reaffirmed its adherence to the Frye test to determine admissibility of novel scientific evidence. State v. Copeland, 130 Wn.2d 244, 261, 922 P.2d 1304 (1996) (citing Frye v. United States, 293 F. 1013, 34 A.L.R. 145 (D.C. Cir. 1923)). Under this test, scientific evidence is admissible if it is generally accepted in the relevant scientific community, but not admissible if there is a significant dispute between qualified experts as to its validity. Id. at 255. Yet, if the evidence does not involve new methods of proof or new scientific principles, then the Frye inquiry is not necessary. State v. Ortiz, 119 Wn.2d 294, 311, 831 P.2d 1060 (1992). Full acceptance of a process in the relevant scientific community obviates the need for a Frye hearing. State v. Russell, 125 Wn.2d 24, 41, 882 P.2d 747 (1994), cert. denied, 514 U.S. 1129, 115 S. Ct. 2004, 131 L. Ed. 2d 1005 (1995).

Here, the trial court held a Frye hearing to determine the admissibility of the prints identified by use of the enhanced digital imaging process. The State presented testimony from two experts, Holshue and Berg, who explained the steps they took to ultimately identify Hayden's palm and fingerprint from the fitted bed sheet. The State also provided the trial court with forensic literature regarding digital image enhancement. Hayden did not present any witnesses at the Frye hearing and presented no controverting literature. Based upon the testimony, the trial court found that the amido black chemical dipping process is generally accepted by forensic scientists and that the enhanced digital imaging process is not novel scientific evidence to which the Frye test applies. Nonetheless, the court also concluded that the enhanced digital imaging process passed the Frye test.

Hayden does not challenge the trial court's rulings with respect to the amido black chemical dipping process. Neither does he challenge the courts rulings under ER 702, that both Holshue and Berg were qualified as experts and that their testimonies would be helpful to the trier of fact. He argues only that the enhanced digital imaging process has not obtained general acceptance in the relevant scientific community because its use for this purpose is recent and because the computer programs used to enhance the images were not designed for forensic science. He maintains that the procedure used to produce the enhanced prints did not satisfy the Frye standard, and, therefore, that the trial court erred in admitting the evidence. The State responds that enhanced digital imaging is not novel. It argues further that even if the process is novel, it is accepted in the latent print examiner's scientific community, thereby satisfying the Frye standard.

A. Novel Scientific Evidence In 1994, the enhanced digital imaging process was described by Berg, the State's digital imaging expert, as "a totally new process based upon research and development done in the late 1960's and early 1970's for the space program." E. Berg, Latent Image Processing - A Changing Technology, PACIFIC NW INT'L ASS'N FOR IDENTIFICATION EXAMINER, 2d Quarter 1994. This and other literature presented reflects that the technology used to enhance photographs of latent prints evolved from jet propulsion laboratories in the NASA space program to isolate galaxies and receive signals from satellites. The Tacoma Police Department began using digital imaging technology in forensics in January of 1995.

The State contends that because the underlying scientific theory behind enhanced digital imaging is not new, its application to forensic science does not constitute a novel process; it suggests that it was merely the high cost of the process that prevented law enforcement organizations from using it earlier. Yet, a 1987 article from the FBI Academy's International Symposium on Latent Prints observed:

Latent print examiners across the country react differently when image enhancement of latent prints is discussed. Often, the initial reaction is one of disapproval. The concern is that nonexistent detail is added to the latent print. Image enhancement techniques are not designed to create detail but to improve images for human interpretation.

A.L. McRoberts, Digital Image Processing as a Means of Enhancing Latent Fingerprints, PROC. OF THE INT'L FORENSIC SYMP. ON LATENT PRINTS, FBI, July 7-10, 1987, at 166. Although this article may not be reflective of the current latent print examiner community because it was written 10 years ago, it indicates that skepticism, in addition to high costs, may have contributed to the delay in the use of digital image enhancement in forensic science.

In support of its argument that the process is not novel, the State relies further upon State v. Noltie, 57 Wn. App. 21, 786 P.2d 332 (1990), aff'd, 116 Wn.2d 831, 809 P.2d 190 (1991). At issue in Noltie was the admissibility of enlarged views of a child abuse victim's sex organs obtained using a colposcope, a microscope developed and used to diagnose cancer. Id. at 28-29. This court concluded: "We find no basis for Noltie's contention that colposcopy constitutes a 'novel' field or scientific technique, even though its use in child abuse cases may be relatively recent." Id. at 29. It called the colposcope "a magnifying glass with a fancy name" and concluded that it was not subject to the Frye test. Id. at 29-30 (citation omitted).

In Noltie, this court cited three cases from other jurisdictions that agreed with its holding. Noltie, 57 Wn. App. at 29-30 (citing one Kentucky case and two California cases). In the instant matter, no court has ruled in a published appellate decision on the admissibility of latent prints processed by enhanced digital imaging.

The only published case that mentions this process is Litaker v. Texas, 784 S.W.2d 739 (Tex. Crim. App. 1990). In Litaker, the Texas Court of Criminal Appeals rejected a sufficiency-of-the-evidence challenge to a conviction involving amido black blood treatment and a computer image enhancing process. Litaker, 784 S.W.2d at 742. A retired United States Army latent print examiner testified as an expert at trial, matching the enhanced latent print with a known print. Id. Because admissibility of this evidence was not challenged in Litaker, the court did not discuss the processes in detail. Nonetheless, Litaker indicates that the enhanced digital imaging process was utilized in at least one court as early as 1990.

Certainly digital photography is not a novel process. Neither is the use of computer software to enhance images. It is only the forensic use of these tools that is relatively new.

Although we find the State's argument that the process is not novel to be persuasive, because this is a question of first impression we analyze the admissibility of the evidence under the Frye standard.

B. The Frye Test [4, 5] Review of admissibility of evidence under the Frye test is de novo. Copeland, 130 Wn.2d at 261. Because no Washington court, and no other court in a published opinion, has determined that the digitally enhanced print process satisfies the Frye test, this court must examine the record, the available literature and cases from other jurisdictions to determine whether enhanced digital imaging is generally accepted in the relevant scientific community State v. Cauthron, 120 Wn.2d 879, 888, 846 P.2d 502 (1993).

To demonstrate that the enhanced digital imaging process is accepted in the relevant scientific community, the State presented the testimony of two expert witnesses at trial and attached five articles from forensic journals to its trial brief. Although Hayden asserts: "[I]t is impossible to conclude that [this] process has obtained general acceptance in the relevant scientific community," App. Br. at 8, he provided no witnesses or documentation to contradict the State's experts at the trial court level and provides no literature or other evidence to this court that contradicts the evidence and literature presented by the State, in spite of the fact that we are not limited to the scientific literature that was before the trial court.

Berg is employed by the Tacoma Police Department as a forensic specialist and had spent the two-and-a-half years prior to this trial specializing in enhanced digital imaging and its application in the field of forensic science. He is the author of two articles on the enhanced digital imaging process: Latent Image Processing - A Changing Technology, PACIFIC NW INT'L ASS'N FOR IDENTIFICATION EXAMINER, 2d Quarter 1994, and The Digital Future of Investigations, L. ENFORCEMENT TECH. Aug. 1995.

At trial and in his articles, Berg explained the process of enhanced digital imaging in detail. See also B.E. Dalrymple & T. Menzies, Computer Enhancement of Evidence Through Background Noise Suppression, 39 J. FORENSIC Sci., Mar. 1994. The advantage of digital photographs, rather than analogue film photographs, is that digital

photography can capture approximately 16 million different colors and can differentiate between 256 shades of gray. Digital photographs work with light sensitivity, just like film photographs, except the computer uses a chip and a hard drive in place of the camera's film. At trial, Berg testified that there is no subjectivity in this process.

The digital photographs are enhanced using software that improves sharpness and image contrast. In addition, pattern and color isolation filters remove interfering colors and background patterns. This is a subtractive process in which elements are removed or reduced; nothing is added. At trial, Berg testified that the software he used prevented him from adding to, changing, or destroying the original image. In contrast with "image restoration," a process in which things that are not there are added based upon preconceived ideas about what the end result should look like, "image enhancement" merely makes what is there more usable. See William J. Watling, Using the FFT in Forensic Digital Image Enhancement, 43 J. FORENSIC IDENT. 574 (1993).

[6, 7] On cross-examination at trial, Berg admitted this was the first time he had ever taken a latent print off of a fabric. Still, nothing in the literature presented to the trial court and for this appeal indicates that the validity of the process depends upon the nature of the material upon which the print is found. We have examined the fabric and the digitally enhanced photographs in the course of our review. It is clear even to the untrained eye that the fabric contains a handprint and that nothing appears in the digitally enhanced photograph that was not present on the fabric. Rather, the image of the handprint is merely enhanced by removing background detail unrelated to the points of identification by which the handprint was identified as Hayden's. The evidence in the record supports the trial court's unchallenged findings that the technique utilized by Berg has a reliability factor of 100 percent and a zero percent margin of error and that the results are visually verifiable and could be easily duplicated by another expert using his or her own digital camera and appropriate computer software.

The literature presented by the State indicates that digital image processing has been used as a means of enhancing latent fingerprints by the Los Angeles County Sheriffs Department since at least 1987. See A.L. McRoberts, Digital Image Processing as a Means of Enhancing Latent Fingerprints, PROC. OF THE INT'L FORENSIC SYMP. ON LATENT PRINTS, July 7-10, 1987, at 165-66. Because there does not appear to be a significant dispute among qualified experts as to the validity of enhanced digital imaging performed by qualified experts using appropriate software, we conclude that the process is generally accepted in the relevant scientific community. Accordingly, we reject Hayden's contention that the trial court erred by admitting the challenged evidence and affirm his conviction.

A majority of the panel having determined that the remainder of this opinion lacks precedential value and will not be printed in the Washington Appellate Reports but will be filed of public record in accord with RCW 2.06.040, it is so ordered.

GROSSE and AGID, JJ., concur.

110 KAHN v. SALERNO Feb. 1998 90 Wn. App. 110, 951 P.2d 321

1

IN THE CIRCUIT COURT OF THE 17TH JUDICIAL CIRCUIT IN AND FOR BROWARD COUNTY, FLORIDA CASE NO: 99-11535CF10A JUDGE: STANTON S. KAPLAN

STATE OF FLORIDA,

Plaintiff, v. VICTOR REYES,

Defendant.

MEMORANDUM OPINION AND ORDER ON DEFENDANT’S MOTION IN LIMINE RE: LATENT FINGERPRINT ANALYSIS

THIS CAUSE having come on to be heard on Defendant’s Motion in Limine Re: Fingerprint Analysis and the response thereto of the State of Florida filed November 27, 2001, and the Court having held a full Frye Hearing thereon in which the Court has heard the testimony of all witnesses called by either party, this Court finds as follows: (1) The defense has asked this Court to grant a motion in limine based upon the fact

that the digital enhancement that occurred in this case does not meet Frye Standards, stating that there is no guarantee of reliability of “new” or “novel” evidence. To demonstrate that the use of digital imaging to enhance a latent print is not new or novel and that it is accepted within the relevant forensic community, the State presented the testimony of three expert witnesses, i.e., Mr. Erik Berg, Mr. David Witzke, and Mr. David Knoerlein. The defense has not been able to provide witnesses or documentation to contradict the State's experts; and the defense has been unable to provide any literature or other evidence that contradicts the testimony and literature presented by the State. In fact, the documentation provided by the defense was misquoted by Ms. Deborah Lynn Rose Myers, and the excerpts were taken out of context. For example, Ms. Myers erred in her discussion about the loss of color information during mode changes by failing to include pertinent and relevant information such

2

as “With a clear understanding of the process, you can avert or offset many of these problems, and use the conversion [RGB to grayscale] as an opportunity to improve the image.” (See page 486, Special Edition Using Adobe Photoshop 6 by Richard Lynch.) At page 487, Ms. Myers failed to include a very pertinent section: A good conversion will keep the elements of a color photo intact after conversion to grayscale, and it will attempt to improve them for grayscale representation. This might require essentially ruining the color to get a better grayscale conversion result. Actually, it is ignoring the color to get a better conversion, not ruining it; when you are converting from color to grayscale the colors themselves no longer matter.

(2) Mr. Berg, developer of the PC Pros MORE HITS program, testified that while digital enhancement of fingerprints is not a new procedure, it has only received widespread acceptance in its application to enhancement of fingerprints within the past ten years. Digital enhancement of video tapes and photographs has been in use and used in courts for more than a decade. More specifically, the International Association for Identification (IAI) passed Resolution 97-9, which states: … the International Association for Identification recognizes that electronic/ digital imaging is a scientifically valid and proven technology for recording, enhancing, and printing images and like conventional silver-halide based photography, it is accepted by professional commercial photographers, law enforcement photographers, and the identification community. This has offered legitimacy to the technology and has encouraged its adoption among the members of the IAI. Since that time, digital imaging technology has spread to nearly every major law enforcement agency in the United States.

(3) This Court also heard testimony from Mr. Witzke, who is considered to be an expert in forensic digital imaging, and is internationally renowned for his training programs in forensic image processing. In his testimony, Mr. Witzke described the standard image enhancement processes and procedures that are taught and followed throughout the United States, Canada and England. Mr. Witzke also testified that he had trained and had cause to review the proficiency of the person who performed the procedures used in this digital enhancement process, Mr. Knoerlein. Mr. Knoerlein testified that he is a forensic analyst with more than 18 years of experience, and is well trained and proficient in the use of the digital image enhancement system, and that he has more than five years of experience in digital

3

imaging. During that time, he has enhanced more than 10,000 images, most of which are latent prints.

(4) The defense has stated that according to the evidence presented, there are no rules or standards regulating the application of digital imaging. We have had testimony that the process of digital imaging is accepted within the forensic community. Mr. Knoerlein testified that the procedures used by the Broward County Sheriff’s Office in no way changes the basic fingerprint image, but only makes the image clearer. He further testified that he follows the standard operating procedures and guidelines established by the Broward County Sheriff’s Office for digital image processing, which states that: …all enhancements shall be performed on exact copies of the original image, and that at no time during the enhancement process will any area of an image be deleted or altered in any way. All enhancement processes shall be accomplished by adjusting the values of each pixel that make up the total image. Each of these processes is then recorded for purposes of authenticating the image enhancement process. Mr. Knoerlein further testified that these procedures follow the Scientific Working Group on Imaging Technologies’ (SWGIT) recommendations and guidelines for the use of digital image processing in the criminal justice system. The stated purpose of the SWGIT guidelines is to ensure the successful introduction of forensic imagery as evidence in a court of law.

(5) In the testimony of Ms. Myers, she stated that there is no documentation that

exists which records the steps that were taken during the enhancement process. Both Messrs Witzke and Knoerlein demonstrated in this Court how that process is documented. Mr. Witzke also testified that the process of recording of digital enhancement processes is actually more thorough than the recording process of traditional photographic processes in which there is no record of any enhancement process, i.e., in traditional darkroom processing there is no record of how long the exposure was, where dodge and burn functions were performed, and so forth.

(6) Both Messrs Witzke and Knoerlein demonstrated to the satisfaction of this Court that the enhancement procedure does not change the basic image. This Court concurs with the reasoning stated by the Washington Court of Appeals in State of Washington v Hayden, 950 Pa2d 1024 (Court of Appeals 1998) that digital enhancement methodology does not involve new scientific principals and should not require a Frye Hearing, but nevertheless the methodology does satisfy the Frye requirements. Three other decisions that support this position were decided in State of Florida, i.e., (1) State of Florida versus Veleka Bryant, a First District case cited at 810 So.2d 532 (Fla. 1st DCA 2002); (2) the State of Florida versus Roger Dolan, a Fourth District case cited at 743 So.2d 544, 546 (Fla. 4th DCA 1999); and (3) the State of Florida versus Lucious Boyd, Case No. 99-

4

5809CF10A, Broward County, Florida, Circuit Court. In another case, United States v. Beeler, 62 F. Supp. 2d 14 (D. Me. 1999), the Court “viewed both the original and enhanced versions of a surveillance tape … were accurate, authentic, and trustworthy representations of the original tape.” And “that they depict the same images and have not been manipulated to impermissibly alter the images.”

(7) Further, Mr. Witzke testified and demonstrated for this Court that the image

enhancement process is simply an automation process that is intended to improve the visual appearance of a duplicate of an original image. He demonstrated in this Court that neither the scanning nor the image enhancement process alters the physical appearance or the contents of the original image captured from the negative. In State v Bryant, the Appellate Court upheld the trial court’s finding that the original time lapse videotapes were authentic based upon testimony by the State’s expert about the nature of the original time-lapse videotape and the enhancements made to a duplicate of the original, time-lapse videotapes. The court went on to define a duplicate as: A counterpart produced by the same impression as the original…by means of photography, including enlargements and miniatures; by mechanical or electronic rerecording; by chemical reproduction; or by equivalent technique that accurately reproduces the original … In United States v. Beeler, 62 F. Supp. 2d 136, 148 (D. Me. 1999), the Court found that “Rerecordings that are enhanced so that the images are clearer to depict [sic] are also ‘duplicates’ so long as the tapes accurately reproduce the original images on the tape.”

(8) This Court heard testimony from Ms. Myers in which she stated that the image

acquired from the original negative was not an original and that it was an altered image. Yet Rule 1001 from the Federal Rules of Evidence serves to define the originality of evidence. Variations of this rule have been adopted by nearly every State in the US. The Texas Rule of Evidence 1001 is typical of how most States have chosen to adopt the Federal Rule: An original of a writing or recording is the writing or recording itself or any counterpart intended to have the same effect by a person executing or issuing it. An original of a photograph includes the negative or any print therefrom. If data are stored in a computer or similar device, any printout or other output readable by sight, shown to reflect the data accurately, is an original. Section 1550.6, added in August of 1996, defines originality of video and digital images by stating:

5

Images stored on video or digital media, or copies of images stored on video or digital media, shall not be rendered inadmissible by the best evidence rule. Printed representations of images stored on video or digital media shall be presumed accurate representations of the images they purport to represent.

(9) The enhancement of the latent image in this case was not extensive and this Court is satisfied that at least two experienced latent fingerprint comparison experts, Messrs Robert Holbrook and James DelValle, have stated in their opinions that a positive identification was made of both the enhanced digital fingerprint image as well as the original digital image with that of the Defendant’s rolled print. Their opinions were contradicted in part by the testimony of two other latent fingerprint examiners, namely Ms. Rena Barry and Ms. Eva Souder, neither of whom claimed that it was a wrong identification, but only that they could not make the identification themselves. Further, this Court recognizes that fingerprint comparison is a technical field that is subject to the experience and proficiency of the examiner, and in any event that the testimony of Ms. Barry and Ms. Souder goes only to the weight to be given the testimony of Mr. Holbrook and Mr. DelValle. Therefore, this Court finds that all four of the examiners are qualified to give their opinions as will be any additional latent print examiners provided they too are shown to be qualified.

(10) In her testimony, Ms. Myers also stated her belief that the Adobe Photoshop software could be used to create fraudulent prints has no basis in fact and the insinuation that it might have been so used is without a factual basis and is highly prejudicial and unwarranted. In Cross v. U.S., 149 F.3d 1190, 1998 WL 255054 (10th Cir. Kan. 1998) the Court (unpublished opinion), stated that the “mere possibility” of tampering was insufficient to prove bad faith. Similarly, in United States v Balzano, 687, F.2d 6, 7-8 (1st Cir. 1982) the Court also approved the trial court’s decision to admit duplicate audiotapes where the defense had alleged that “hypothetically” tampering could have occurred. Furthermore, the fundamental, principal requirements for admitting a photograph into evidence — whether it is digital or film-based — are relevance and authentication. Mr. Knoerlein testified that the digital photograph was an accurate representation of the image captured on the negative, and Mr. Witzke demonstrated for this Court that the MORE HITS program could successfully authenticate the image.

(11) In another excerpt from the documentation provided by the defense, Ms. Myers

read into record (read from page 201, Forensic Digital Imaging and Photography by Herbert L. Blitzer and Jack Jacobia):

6

Anyone who has seen a movie made in the past five years is well aware that it is possible to do almost anything you want to do with digital images—change which items are in the picture, change their coloration or texture, move things around, etc.; thus it is generally believed that the digital images are easily manipulated. At the same time, there is a belief that film images are much less susceptible to manipulation. The facts of the matter are that the first statement is true and the second is, to a large degree, false. Ms. Myers failed to include the final sentence of that paragraph, which reads: Furthermore, in a well-run lab, where proper procedures are followed, one can argue that the digital images are in fact more secure than the film images.

(12) In the initial testimony of Ms. Myers, she testified in error that pixels were both

added and then deleted during both the scanning and the enhancement process. In rebuttal, she changed her testimony and stated that only color information was lost. She further stated that a change in file size physically alters the image. However, Mr. Witzke successfully demonstrated for this Court that the change in file size was directly related to changing the color mode of the image from 24-bit color to 8-bit grayscale, and did not alter the image.

(13) In both her initial testimony and rebuttal, Ms. Myers erred in her statements that dodge and burn functions could not be performed on a 24-bit color image and that the image had to be taken through a mode change to 8-bit grayscale to perform these functions. Mr. Witzke successfully demonstrated for this Court that a mode change is not necessary and that these functions can indeed be performed successfully and effectively on either a 24-bit color image or an 8-bit grayscale image.

(14) This Court finds that the process of digital enhancement of fingerprints used in this case, i.e., the “MORE HITS software program” is currently being used by the Federal Bureau of Federal Bureau of Investigation (FBI), US Department of Justice Drug Enforcement Agency (DEA), US Department of Treasury Inspector General for Tax Administration (TIGTA) (Formerly the IRS), US Postal Inspection Services, United States Air Force Office of Special Investigations (USAF OSI), United States Army Crime Lab, United States Customs, the United States Secret Service as well as more than 150 different state and municipal law enforcement agencies throughout the United States, and it is also being used in Canada and England.

(15) This Court finds that there is no reason to depart from the accepted law in Florida and in all other States and Federal Courts in the United States of allowing into evidence the opinion of duly qualified experts as to the identification of a latent fingerprint with that of a known rolled fingerprint.

7

(16) This Court finds that there are specific rules and standards that govern the use of digital images, including but not limited to the minimum accepted resolution of digital images. These standards are published as the FBI’s guidelines regarding digital image quality standards, and have been accepted within the fingerprint community for more than two decades.

(17) This Court finds that Automated Fingerprint Identification Systems (AFIS), which is based on digital imaging technologies, have been used successfully throughout the United States and Canada to digitally record, enhance, store and manage fingerprints for more than 30 years.

(18) This Court finds that the testimony of Simon H. Cole, PhD., would not be helpful to the jury in this case and would only tend to confuse the jury. Dr. Cole’s testimony can be summarized as his opinion based on his unsubstantiated readings and studies that the current methodology used in making fingerprint comparisons is unreliable, subject to error, and has not been scientifically tested. This Court takes note that Dr. Cole has no personal experience or training in fingerprint comparison methodology. This Court draws the obvious comparison that his testimony would be similar to expert testimony as to the unreliability of eye-witness testimony which has been disallowed. This Court will not permit the testimony of Dr. Cole to be presented before the Jury.

(19) Finally, this Court finds that the testimony of Debra Lynn Rose Myers would not be helpful to the jury in this case and would only tend to confuse the jury. Ms. Myers acknowledged her total lack of knowledge of fingerprint comparison methodology, and in particular the methodology used in this case, i.e., the MORE HITS software program. She also acknowledged her total lack of formal training in digital imaging and stated that she is solely self-taught in the use of Adobe Photoshop. She further acknowledged that she has absolutely no knowledge of nor has she ever performed any traditional darkroom photo processing. Ms. Myers’ applied expertise in the use of Adobe Photoshop is in the area of graphic arts/graphic design. While the Adobe Photoshop software is an integral part of the MORE HITS system, its use and purpose is totally different that the use and purpose of Adobe Photoshop in the area of graphic arts/graphic design. Further, while the exact color calibration for perfect color reproduction may be critical in some applications, it has only limited meaning and value in the current case. Ms. Myers’ use of Adobe Photoshop is so totally different from that used by the MORE HITS program that her testimony could only serve to mislead the jury. Therefore, this Court finds that Ms. Myers is not qualified to render an opinion on

8

the subject, i.e., the methodology of digital enhancement of fingerprints. This Court will not permit the testimony of Ms. Myers to be presented before the jury.

ACCORDINGLY, it is hereby, ORDERED AND ADJUDGED that the said Defense Motion in Limine is denied. DONE AND ORDERED in chambers in Broward County, Fort Lauderdale this ___ day of ______________________, 2002.

____________________________________ STANTON S. KAPLAN CIRCUIT COURT JUDGE

cc: Thomas F. Kern, A.S.A. Barbara A. Heyer, Esq.

Section 1 Guidelines for Imaging ... - CFI trainer...subjected to image analysis. (See...

Documents

Transcript of Section 1 Guidelines for Imaging ... - CFI trainer...subjected to image analysis. (See...