Digital Image Processing

04/19/2304/19/23 Duong Anh Duc - Digital Image ProcessingDuong Anh Duc - Digital Image Processing 11

Digital Image Processing

What is a digital image?


What is a digital image?

What is an image? – Picture, Photograph – Visual data Visual data – Usually two- or three-dimensional Usually two- or three-dimensional

What is a digital image? What is a digital image? – An image which is “discretized,” i.e., defined on a An image which is “discretized,” i.e., defined on a

discrete grid (ex. scanner) discrete grid (ex. scanner) – Two-dimensional collection of light intensity values Two-dimensional collection of light intensity values

(or gray values) (or gray values) – Matrix, two-dimensional function Matrix, two-dimensional function


What is digital image processing?What is digital image processing?

What is digital image processing? What is digital image processing? – Digital image processing deals with the Digital image processing deals with the

manipulation and analysis of pictures by a manipulation and analysis of pictures by a computer. computer.

– Improve pictorial information for better clarity Improve pictorial information for better clarity (human interpretation). (human interpretation).

– Automatic machine processing of scene data Automatic machine processing of scene data (interpretation by a machine/non-human, (interpretation by a machine/non-human, storage, transmission). storage, transmission).


Important steps in a typical image Important steps in a typical image processing systemprocessing system

Image Acquisition

Discretization/Digitization Quantization Compression

Image enhancement and restoration

Image Segmentation

Feature Selection

Image Representation

Image Interpretation

Partition image into objects or constituent parts

Extracting pertinent features (or descriptors) from an image that are important for differentiating one class of objects from another

Assigning labels to an object based on information provided by descriptors

Assigning meaning to an ensemble of recognized objects

Capturing visual data by an imaging sensor

Convert data into discrete form Compress for efficient storage/transmission

Improving image quality (low contrast, blur, noise)


Image Processing and Analysis Image Processing and Analysis TransformationsTransformations

Level 0: Level 0: Image representation (acquisition, Image representation (acquisition, sampling, quantization, compression)sampling, quantization, compression)

Level 1: Level 1: Image-to-image transformations Image-to-image transformations (enhancement, restoration, segmentation) (enhancement, restoration, segmentation)

Level 2:Level 2: Image-to-parameter transformation Image-to-parameter transformation (feature selection) (feature selection)

Level 3:Level 3: Parameter-to-decision transformation Parameter-to-decision transformation (recognition and interpretation) (recognition and interpretation)


Image Processing and Analysis Image Processing and Analysis TransformationsTransformations

Image Processing:Image Processing: Levels 0 and 1 Levels 0 and 1 Image Analysis:Image Analysis: Levels 1 and 2 Levels 1 and 2 Computer/Robot VisionComputer/Robot Vision:: Levels 2 and 3 Levels 2 and 3 Computer Graphics/Animation ?Computer Graphics/Animation ?

– This mainly involves “creating images” or “visual This mainly involves “creating images” or “visual effects” from a given description. effects” from a given description.

Image processing and analysis is mainly Image processing and analysis is mainly concerned with “interpreting” a given image. concerned with “interpreting” a given image.


Images come from various Images come from various applicationsapplications

Engineering --- Circuit board



Medicine --- MR Scan



Photography



Astronomy


Some Image Processing Some Image Processing Examples - Gamma-Ray ImagingExamples - Gamma-Ray Imaging

Gamma-ray imaging is used in many Gamma-ray imaging is used in many applications like nuclear medicine and applications like nuclear medicine and astronomy. astronomy.

Positron emission tomography (PET imaging) is Positron emission tomography (PET imaging) is commonly used in medical diagnostic imaging. commonly used in medical diagnostic imaging.

Radioactive isotope administered to patient, Radioactive isotope administered to patient, which emits positrons. which emits positrons.

Positron and electron meet and annihilate, Positron and electron meet and annihilate, giving out gamma-rays, which are detected by giving out gamma-rays, which are detected by sensors. sensors.

Prominent bright spots indicate white masses Prominent bright spots indicate white masses corresponding to tumors in lung and brain.corresponding to tumors in lung and brain.


X-Ray ImagingX-Ray Imaging


Basic Chest X-RayBasic Chest X-Ray

X-ray imaging is used in a number of areas X-ray imaging is used in a number of areas like medical diagnostics, astronomy, and industrial like medical diagnostics, astronomy, and industrial applications. applications.

X-rays generated by a X-ray tube (vacuum X-rays generated by a X-ray tube (vacuum tube) pass through the object to be imaged and tube) pass through the object to be imaged and is then captured by a sensor. is then captured by a sensor.

If an X-ray film is used as the sensor, it is If an X-ray film is used as the sensor, it is typically digitized to get a digital image. typically digitized to get a digital image.

Alternatively, the X-rays are captured by Alternatively, the X-rays are captured by devices that convert it into light energy which devices that convert it into light energy which is then sent to a lightsensitivedigitizing system. is then sent to a lightsensitivedigitizing system.


Contrast Enhancement Contrast Enhancement radiographyradiography

A catheter is inserted in a A catheter is inserted in a blood vessel to be blood vessel to be studied. studied.

X-ray contrast medium X-ray contrast medium is injected through the is injected through the catheter to enhance the catheter to enhance the contrast of the blood contrast of the blood vessels. vessels.

Aortic angiogramAortic angiogram


Industrial ApplicationIndustrial Application

Circuit Board


Remote SensingRemote Sensing


Band no.Band no. NameName Wavelength Wavelength

(mm) (mm)

Characteristic and Use Characteristic and Use

11 Visible BlueVisible Blue 0.45-0.52 0.45-0.52 Maximum water penetrationMaximum water penetration

22 Visible GreenVisible Green 0.52-0.60 0.52-0.60 Good for measuring plant vigor Good for measuring plant vigor

33 Visible RedVisible Red 0.63-0.69 0.63-0.69 Vegetation Discrimination Vegetation Discrimination

44 Near infrared Near infrared 0.76-0.900.76-0.90 Biomass and shoreline mapping Biomass and shoreline mapping

55 Middle infrared Middle infrared 1.55-1.75 1.55-1.75 Moisture content of soil and Moisture content of soil and vegetation vegetation

66 Thermal infrared Thermal infrared 10.4-12.5 10.4-12.5 Soil moisture; thermal mapping Soil moisture; thermal mapping

77 Middle infraredMiddle infrared 2.08-2.35 2.08-2.35 Mineral mapping Mineral mapping


Other Applications – Other Applications – Finger print image Finger print image


License Plate reader License Plate reader


Application AreasApplication Areas

Biological Sciences Biological Sciences Meteorology/Satellite Imaging Meteorology/Satellite Imaging Material Sciences Material Sciences Medicine Medicine Industrial inspection/Quality Control Industrial inspection/Quality Control Geology Geology Astronomy Astronomy Military Military Physics/Chemistry Physics/Chemistry Photography Photography

Digital Image Processing

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