David E. Pitts CSCI 5532 Overview of Image Processing by David E. Pitts Aug 22, 2010 copyright 2005, 2006, 2007, 2008, 2009, 2010

David E. Pitts CSCI 5532 A Digital Image is an Array of Numbers Spatially Arranged in a Predetermined Fashion Each number in the Array represents one Picture Element

David E. Pitts CSCI 5532 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 CSCI 5532 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 CSCI 5532 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 CSCI 5532 Approach for Removing Artifacts - Use off the shelf applicaitons - Photoshop - NIH Image - Multispec - Dimple - Develop your own algorithms based on fundamental principles

David E. Pitts CSCI 5532 Mathematical Operators Used in Imaging Addition Subtraction Multiplication Division Linear Transforms Non-Linear Transforms Differentiation Integration Fourier Transforms Morphological Operators Boolean Operators

David E. Pitts CSCI 5532 Because of the Nature of Digital Images Operators are Discrete (e.g. Integration is replaced by Summation) Operations can be: Between Two or More Images Over an Entire Image Within a Window ≥ 2 x 2 pixels

David E. Pitts CSCI 5532 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 Features Association of Patterns (e.g. Shadows)

David E. Pitts CSCI 5532 Purpose of Imaging Processing Correct Image Defects Blurring Distortions Improve Brightness or Contrast Improve Color Minimize Noise Remove Non-Uniform Lumination

David E. Pitts CSCI 5532 Purpose of Imaging Processing (cont.) Segmentation of Image (Isolate Desired Features in order to determine characteristics) Size Location Shape Orientation Perimeter Major and Minor Dimensions

David E. Pitts CSCI 5532 Single Pixel Operations Within One Digital Image

David E. Pitts CSCI 5532 Single Pixel Operations Within One Digital Color Image

David E. Pitts CSCI 5532 Linear Algebraic Operations Between Digital Images

David E. Pitts CSCI 5532 Operations Within Windows in One Digital Image

David E. Pitts CSCI 5532 Operations Within Windows in One Digital Image Example: Edge Enhancement of the function g(x,y) Laplacian =

David E. Pitts CSCI 5532 Operations Within Windows in One Digital Image Median Filter = Sort Values from Pixels in Window

David E. Pitts CSCI 5532 Operations Within Windows in One Digital Image Average Value Filter

David E. Pitts CSCI 5532 TEXTURE INFORMATION TECHNIQUES GRAY LEVEL STATISTICS FOURIER POWER SPECTRUM GRAY LEVEL DIFFERENCE STATISTICS DECORRELATION METHODS MARKOV RANDOM FILED

David E. Pitts CSCI X 3 WINDOW WITH GRAY LEVEL 0 TO 3

David E. Pitts CSCI 5532 A GREY LEVEL CO-OCCURRENCE MATRIX (P ) IS DEVELOPED FOR THE DESIRED ORIENTATION HORIZONTAL, VERTICAL, OR DIAGONAL.

David E. Pitts CSCI 5532 MANY MEASURES OF TEXTURE CAN BE USED ANGULAR SECOND MOMENT ∑ { P /R } ENTROPY ∑ { P /R } LOG { P /R }

David E. Pitts CSCI 5532 INVERSE DIFFERENCE MOMENT ∑ { P /R }/{1/(1+(I-J) )} AD HOC CHOICES OF # OF GREY LEVELS, ANGULAR ORIENTATION AND SIZE OF WINDOW MUST BE MADE ACCORDING THE TEXTURE TO BE DETECTED

David E. Pitts CSCI 5532 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 arranged in a circle around the scene. At any given time morphing techniques can be utilized to “fly around the scene”.

David E. Pitts CSCI 5532 Image Processing Software Photoshop by Adobe is the most widely used software. Cost $599 Photoshop 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 Asiva Photo by Shapiro Consulting - Windows $378 LuminaXYs by Tetrix Technologies - Mac & Windows $99 Dfine Photoshop plug-in for noise reduction iCorrect Professional 4.0 by Pictographics Mac & Windows $79 PhotoKit by Pixel Genius is a Photoshop plug-in, Mac & Windows $49