Image processing Presentation

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Image processing Gongalez

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  • As opposed to [0..255]
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  • Image processing Presentation

    1. 1. Image Processing Ref: Digital image processing ,Gonzalez & Woods
    2. 2. Components of an Image Processing System: Ref: Digital image processing ,Gonzalez & Woods
    3. 3. Image sensing 1. a physical device that is sensitive to the energy radiated by the object. 2. a digitizer <ul><li>Technologies used </li></ul><ul><li>1. Photo chemical, eg: photographic film </li></ul><ul><li>2. Photo electronic </li></ul><ul><li>The devices used </li></ul><ul><li>Still camera </li></ul><ul><li>TV camera </li></ul><ul><li>3. X ray scanner </li></ul><ul><li>4. Radar </li></ul><ul><li>5. Magnetic resonance imaging (MRI) system. </li></ul>
    4. 4. Digitizer: Ref: Digital image processing ,Gonzalez & Woods Commonly used digitizers 1. Microdensitometer and 2. flying spot scanner.
    5. 5. 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.
    6. 6. 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.
    7. 7. Structure of the Human Eye
    8. 8. Ref: Digital image processing ,Gonzalez & Woods
    9. 9. Ref: Digital image processing ,Gonzalez & Woods
    10. 10. Ref: Digital image processing ,Gonzalez & Woods
    11. 11. Ref: Digital image processing ,Gonzalez & Woods
    12. 12. Ref: Digital image processing ,Gonzalez & Woods
    13. 13. Ref: Digital image processing ,Gonzalez & Woods
    14. 14. Ref: Digital image processing ,Gonzalez & Woods
    15. 15. Ref: Digital image processing ,Gonzalez & Woods
    16. 16. Ref: Digital image processing ,Gonzalez & Woods
    17. 17. Ref: Digital image processing ,Gonzalez & Woods
    18. 18. Ref: Digital image processing ,Gonzalez & Woods
    19. 19. Image Formation
    20. 20. Sampling and Quantization
    21. 21. Sampling and Quantization
    22. 22. Ref: Digital image processing ,Gonzalez & Woods
    23. 23. 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.
    24. 24. Ref: Digital image processing ,Gonzalez & Woods
    25. 25. Ref: Digital image processing ,Gonzalez & Woods
    26. 26. Ref: Digital image processing ,Gonzalez & Woods
    27. 27. Ref: Digital image processing ,Gonzalez & Woods
    28. 28. Ref: Digital image processing ,Gonzalez & Woods
    29. 29. Ref: Digital image processing ,Gonzalez & Woods
    30. 30. Ref: Digital image processing ,Gonzalez & Woods Aliasing and Moiré Patterns:
    31. 31. Ref: Digital image processing ,Gonzalez & Woods Zooming and Shrinking Digital Images: <ul><li>Zooming </li></ul><ul><li>creation of new pixel locations </li></ul><ul><li>assignment of gray levels to those new locations. </li></ul><ul><li>1.Nearest neighbor interpolation </li></ul><ul><li>2. Pixel replication </li></ul><ul><li>3. Bilinear interpolation </li></ul><ul><li>v(x', y') = ax' + by' + cx'y' + d </li></ul><ul><li>a= f (1, 0)- f (0, 0) </li></ul><ul><li>b= f (0, 1)- f (0, 0) </li></ul><ul><li>c= f (0, 0)- f (1, 0)- f (0, 1)+ f (1, 1) </li></ul><ul><li>d= f (0, 0) </li></ul><ul><li>Image shrinking </li></ul>
    32. 32. Ref: Digital image processing ,Gonzalez & Woods
    33. 33. Ref: Digital image processing ,Gonzalez & Woods   2D bilenear interpolation                                                                                                        Original   Before After No Interpolation
    34. 34. Ref: Digital image processing ,Gonzalez & Woods
    35. 35. Ref: Digital image processing ,Gonzalez & Woods
    36. 36. Basic Point Processing
    37. 37. Ref: Digital image processing ,Gonzalez & Woods
    38. 38. Log
    39. 39. Power-law transformations
    40. 40. Gamma Correction Gamma Measuring Applet: http:// www.cs.berkeley.edu/~efros/java/gamma/gamma.html
    41. 41. Ref: Digital image processing ,Gonzalez & Woods
    42. 42. Image Enhancement
    43. 43. Contrast Streching
    44. 44. Ref: Digital image processing ,Gonzalez & Woods
    45. 45. Ref: Digital image processing ,Gonzalez & Woods
    46. 46. Ref: Digital image processing ,Gonzalez & Woods
    47. 47. Ref: Digital image processing ,Gonzalez & Woods
    48. 48. Histogram Equalization
    49. 49. Ref: Digital image processing ,Gonzalez & Woods
    50. 50. Ref: Digital image processing ,Gonzalez & Woods
    51. 51. Ref: Digital image processing ,Gonzalez & Woods
    52. 52. Ref: Digital image processing ,Gonzalez & Woods Periodic noise
    53. 53. Ref: Digital image processing ,Gonzalez & Woods
    54. 54. Mean and variance of the gray levels in image strips
    55. 55. Ref: Digital image processing ,Gonzalez & Woods
    56. 56. Ref: Digital image processing ,Gonzalez & Woods
    57. 57. Ref: Digital image processing ,Gonzalez & Woods Wrong sign for Q
    58. 58. Ref: Digital image processing ,Gonzalez & Woods
    59. 59. Ref: Digital image processing ,Gonzalez & Woods Max and Min filter
    60. 60. Ref: Digital image processing ,Gonzalez & Woods Alpha trimmed mean filter with d=5
    61. 61. Ref: Digital image processing ,Gonzalez & Woods Adaptive noise reduction filtering
    62. 62. Ref: Digital image processing ,Gonzalez & Woods
    63. 63. What is an image? <ul><li>We can think of an image as a function, f , from R 2 to R: </li></ul><ul><ul><li>f ( x, y ) gives the intensity at position ( x, y ) </li></ul></ul><ul><ul><li>Realistically, we expect the image only to be defined over a rectangle, with a finite range: </li></ul></ul><ul><ul><ul><li>f : [ a , b ] x [ c , d ]  [0,1] </li></ul></ul></ul><ul><li>A color image is just three functions pasted together. We can write this as a “vector-valued” function: </li></ul>
    64. 64. Images as functions
    65. 65. What is a digital image? <ul><li>We usually operate on digital ( discrete ) images: </li></ul><ul><ul><li>Sample the 2D space on a regular grid </li></ul></ul><ul><ul><li>Quantize each sample (round to nearest integer) </li></ul></ul><ul><li>If our samples are  apart, we can write this as: </li></ul><ul><li>f [ i , j ] = Quantize{ f ( i  , j  ) } </li></ul><ul><li>The image can now be represented as a matrix of integer values </li></ul>
    66. 66. Image processing <ul><li>An image processing operation typically defines a new image g in terms of an existing image f. </li></ul><ul><li>We can transform either the range of f . </li></ul><ul><li>Or the domain of f : </li></ul><ul><li>What kinds of operations can each perform? </li></ul>
    67. 67. Point Processing <ul><li>The simplest kind of range transformations are these independent of position x,y: </li></ul><ul><li>g = t(f) </li></ul><ul><li>This is called point processing. </li></ul><ul><li>What can they do? </li></ul><ul><li>What’s the form of t ? </li></ul><ul><li>Important: every pixel for himself – spatial information completely lost! </li></ul>
    68. 68. Image Histograms
    69. 69. Cumulative Histograms
    70. 70. Histogram Matching
    71. 71. Match-histogram code
    72. 72. Neighborhood Processing (filtering) <ul><li>Q: What happens if I reshuffle all pixels within the image? </li></ul><ul><li>A: It’s histogram won’t change. No point processing will be affected… </li></ul><ul><li>Need spatial information to capture this. </li></ul>
    73. 73. Programming Assignment #1 <ul><li>Easy stuff to get you started with Matlab </li></ul><ul><ul><li>James will hold tutorial this week </li></ul></ul><ul><li>Distance Functions </li></ul><ul><ul><li>SSD </li></ul></ul><ul><ul><li>Normalized Correlation </li></ul></ul><ul><li>Bells and Whistles </li></ul><ul><ul><li>Point Processing (color?) </li></ul></ul><ul><ul><li>Neighborhood Processing </li></ul></ul><ul><ul><li>Using your data (3 copies!) </li></ul></ul><ul><ul><li>Using your data (other images) </li></ul></ul>

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