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Image processing Gongalez

Image processing Gongalez

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Image processing Presentation Image processing Presentation Presentation Transcript

  • Image Processing Ref: Digital image processing ,Gonzalez & Woods
  • Components of an Image Processing System: Ref: Digital image processing ,Gonzalez & Woods
  • Image sensing 1. a physical device that is sensitive to the energy radiated by the object. 2. a digitizer
    • Technologies used
    • 1. Photo chemical, eg: photographic film
    • 2. Photo electronic
    • The devices used
    • Still camera
    • TV camera
    • 3. X ray scanner
    • 4. Radar
    • 5. Magnetic resonance imaging (MRI) system.
  • Digitizer: Ref: Digital image processing ,Gonzalez & Woods Commonly used digitizers 1. Microdensitometer and 2. flying spot scanner.
  • Digital storage : Ref: Digital image processing ,Gonzalez & Woods categorized as (1) short-term storage for use during processing, eg: frame buffers. (2) on-line storage for relatively fast re-call, and (3) archival storage, characterized by infrequent access.
  • Image displays: Ref: Digital image processing ,Gonzalez & Woods Principal display devices are 1. printers, 2.TV monitor, 3. CRTs Hardcopy: laser printers, film cameras, heat-sensitive devices, inkjet units, and digital units, such as optical and CD-ROM disks, paper etc.
  • Structure of the Human Eye
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods
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  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods
  • Image Formation
  • Sampling and Quantization
  • Sampling and Quantization
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods Spatial and Gray-Level Resolution: Spatial Resolution: is the smallest discernible detail in an image. Gray—level resolution: refers to the smallest discernible change in gray level . -subjective process.
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods Aliasing and Moiré Patterns:
  • Ref: Digital image processing ,Gonzalez & Woods Zooming and Shrinking Digital Images:
    • Zooming
    • creation of new pixel locations
    • assignment of gray levels to those new locations.
    • 1.Nearest neighbor interpolation
    • 2. Pixel replication
    • 3. Bilinear interpolation
    • v(x', y') = ax' + by' + cx'y' + d
    • a= f (1, 0)- f (0, 0)
    • b= f (0, 1)- f (0, 0)
    • c= f (0, 0)- f (1, 0)- f (0, 1)+ f (1, 1)
    • d= f (0, 0)
    • Image shrinking
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods   2D bilenear interpolation                                                                                                        Original   Before After No Interpolation
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods
  • Basic Point Processing
  • Ref: Digital image processing ,Gonzalez & Woods
  • Log
  • Power-law transformations
  • Gamma Correction Gamma Measuring Applet: http:// www.cs.berkeley.edu/~efros/java/gamma/gamma.html
  • Ref: Digital image processing ,Gonzalez & Woods
  • Image Enhancement
  • Contrast Streching
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods
  • Histogram Equalization
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods Periodic noise
  • Ref: Digital image processing ,Gonzalez & Woods
  • Mean and variance of the gray levels in image strips
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods Wrong sign for Q
  • Ref: Digital image processing ,Gonzalez & Woods
  • Ref: Digital image processing ,Gonzalez & Woods Max and Min filter
  • Ref: Digital image processing ,Gonzalez & Woods Alpha trimmed mean filter with d=5
  • Ref: Digital image processing ,Gonzalez & Woods Adaptive noise reduction filtering
  • Ref: Digital image processing ,Gonzalez & Woods
  • What is an image?
    • We can think of an image as a function, f , from R 2 to R:
      • f ( x, y ) gives the intensity at position ( x, y )
      • Realistically, we expect the image only to be defined over a rectangle, with a finite range:
        • f : [ a , b ] x [ c , d ]  [0,1]
    • A color image is just three functions pasted together. We can write this as a “vector-valued” function:
  • Images as functions
  • What is a digital image?
    • We usually operate on digital ( discrete ) images:
      • Sample the 2D space on a regular grid
      • Quantize each sample (round to nearest integer)
    • If our samples are  apart, we can write this as:
    • f [ i , j ] = Quantize{ f ( i  , j  ) }
    • The image can now be represented as a matrix of integer values
  • Image processing
    • An image processing operation typically defines a new image g in terms of an existing image f.
    • We can transform either the range of f .
    • Or the domain of f :
    • What kinds of operations can each perform?
  • Point Processing
    • The simplest kind of range transformations are these independent of position x,y:
    • g = t(f)
    • This is called point processing.
    • What can they do?
    • What’s the form of t ?
    • Important: every pixel for himself – spatial information completely lost!
  • Image Histograms
  • Cumulative Histograms
  • Histogram Matching
  • Match-histogram code
  • Neighborhood Processing (filtering)
    • Q: What happens if I reshuffle all pixels within the image?
    • A: It’s histogram won’t change. No point processing will be affected…
    • Need spatial information to capture this.
  • Programming Assignment #1
    • Easy stuff to get you started with Matlab
      • James will hold tutorial this week
    • Distance Functions
      • SSD
      • Normalized Correlation
    • Bells and Whistles
      • Point Processing (color?)
      • Neighborhood Processing
      • Using your data (3 copies!)
      • Using your data (other images)