David E. Pitts CSCI 5532 Overview of Image Processing by David E. Pitts Aug 22, 2010 copyright 2005,...
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Transcript of David E. Pitts CSCI 5532 Overview of Image Processing by David E. Pitts Aug 22, 2010 copyright 2005,...
David E. Pitts
CSCI 5532CSCI 5532
Overview of Image Processing
by David E. Pitts
Aug 22, 2010copyright 2005, 2006, 2007, 2008, 2009, 2010
David E. Pitts
CSCI 5532CSCI 5532
A Digital Image is an Array of Numbers Spatially Arranged in a Predetermined FashionEach number in the Array represents one Picture Element
One Pixel
David E. Pitts
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Digital Image
-Light intensity across the image is a function of x and
-grey level range in each pixel is often 8 bits (256 grey levels)(the human eye resolves about 32)
David E. Pitts
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Sources of Images
- Film Cameras (film is sensitive from 0.3 to 0.9 µm)-transparencies-prints
-Video Cameras (silicon is sensitive into near infrared 1.1 µm)-X-rays (e.g. Computerized Tomography)-MRI (Magnetic Resonance Imaging)-Ultrasound (medical images)-Infrasound-Seismic-Aircraft and Spacecraft scanners-Telescopes
-Radio, Optical, Gamma Ray, X-ray-Positron Emission Tomography
David E. Pitts
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Image Artifacts
-Random noise (e.g. blank TV screen)
-Periodic Noise (e.g. herringbone patterns)
-Poor gain (image is too bright or too dark)
-Poor contrast (image is too uniform in brightness)
-Nonuniform response across image (e.g. corners darker than center)
-Smear (e.g. subject moving during image acquisition)
-Curvature of field (e.g. fish eye lens)
- Poor Color
David E. Pitts
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Approach for Removing Artifacts
- Use off the shelf applicaitons- Photoshop http://www.adobe.com/
- NIH Image http://rsbweb.nih.gov/nih-image/
- Multispec http://dynamo.ecn.purdue.edu/~biehl/MultiSpec/
- Dimple http://www.process.com.au/AboutDIMPLE.shtml
- Develop your own algorithms based on fundamental principles
David E. Pitts
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Mathematical Operators Used in Imaging
AdditionSubtractionMultiplicationDivision
Linear TransformsNon-Linear Transforms
DifferentiationIntegration
Fourier Transforms
Morphological Operators
Boolean Operators
David E. Pitts
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Because of the Nature of Digital ImagesOperators are Discrete (e.g. Integration is replaced by Summation)
Operations can be:Between Two or More ImagesOver an Entire ImageWithin a Window ≥ 2 x 2 pixels
David E. Pitts
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Operations Can Involve Any One of Many Characteristics of an Image
Grey Scale Content (Brightness and Contrast)Color Content (Hue and Saturation)Geometry of Image (2 D, 3 D)Frequency Content of Image (e.g. Noise, Edges, Texture)Shapes of FeaturesAssociation of Patterns (e.g. Shadows)
David E. Pitts
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Purpose of Imaging Processing
Correct Image DefectsBlurringDistortionsImprove Brightness or ContrastImprove ColorMinimize NoiseRemove Non-Uniform Lumination
David E. Pitts
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Purpose of Imaging Processing (cont.)
Segmentation of Image (Isolate Desired Features in order to determine characteristics)
SizeLocationShapeOrientationPerimeterMajor and Minor Dimensions
David E. Pitts
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Single Pixel Operations Within One Digital Color Image
Operation
RG
B
RG
B
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Linear Algebraic Operations Between Digital Images
Operation
X Y Z
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Operations Within Windows in One Digital Image
Example: Edge Enhancement of the function g(x,y)
Laplacian =
David E. Pitts
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Operations Within Windows in One Digital Image
Median Filter = Sort Values from Pixels in Window
David E. Pitts
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Operations Within Windows in One Digital Image
Average Value Filter
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TEXTURE INFORMATION TECHNIQUES
GRAY LEVEL STATISTICS
FOURIER POWER SPECTRUM
GRAY LEVEL DIFFERENCE STATISTICS
DECORRELATION METHODS
MARKOV RANDOM FILED
David E. Pitts
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A GREY LEVEL CO-OCCURRENCE MATRIX (P )IS DEVELOPED FOR THE DESIRED ORIENTATIONHORIZONTAL, VERTICAL, OR DIAGONAL.
i j
REPRESENTS THE NUMBER OF TIMES i and jARE NEIGHBORS
0 1 2 3 i
0
1
2
3
j
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MANY MEASURES OF TEXTURE CAN BE USED
ANGULAR SECOND MOMENT
∑ { P /R }
ENTROPY
∑ { P /R } LOG { P /R }
2
i j
i j
i j
i j
i j
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INVERSE DIFFERENCE MOMENT
∑ { P /R }/{1/(1+(I-J) )}
AD HOC CHOICES OF # OF GREY LEVELS,ANGULAR ORIENTATION AND SIZE OF WINDOWMUST BE MADE ACCORDING THE TEXTURE TOBE DETECTED
i ji j
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Multiple viewing angle videography
Developed by Carnegie Mellon School of Computer Science
Technique was first used at 2001 Superbowl
Technique uses many synchronized video cameras arrangedin a circle around the scene. At any given time morphing techniques can be utilized to “fly around the scene”.
http://www.cs.cmu.edu/virtualized-reality/main.html
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Image Processing Software
Photoshop by Adobe is the most widely used software. Cost $599Photoshop Elements by Adobe contains most commonly used features of
Photoshop. Mac & Windows, Cost $89
Other Image Processing Software was reviewed in the March/April 2003 issue of Photoelectronic Imaging, pg 14-15.
Asiva Photo by Shapiro Consulting - Windows $378LuminaXYs by Tetrix Technologies - Mac & Windows $99Dfine Photoshop plug-in for noise reduction www.nikmultimedia.comiCorrect Professional 4.0 by Pictographics Mac & Windows $79PhotoKit by Pixel Genius is a Photoshop plug-in, Mac & Windows $49