Introduction To Advanced Image Processing

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Introduction To Advanced Image Processing

  1. 1. Introduction to Advanced Image Processing Suren Kumar [email_address]
  2. 2. Convolution Filter <ul><li>Filtering is a technique for modifying or enhancing an image. For example, you can filter an image to emphasize certain features or remove other features. </li></ul><ul><li>Filtering is a neighborhood operation, in which the value of any given pixel in the output image is determined by applying some algorithm to the values of the pixels in the neighborhood of the corresponding input pixel. </li></ul><ul><li>Linear filtering is filtering in which the value of an output pixel is a linear combination of the values of the pixels in the input pixel's neighborhood. </li></ul>
  3. 3. Convolution Filter <ul><li>Let the image be </li></ul><ul><li>A = [17 24 1 8 15 </li></ul><ul><li>23 5 7 14 16 </li></ul><ul><li>4 6 13 20 22 </li></ul><ul><li>10 12 19 21 3 </li></ul><ul><li>11 18 25 2 9] </li></ul><ul><li>and the convolution kernel is h = [8 1 6 </li></ul><ul><li> 3 5 7 </li></ul><ul><li> 4 9 2] </li></ul>
  4. 4. Convolution Filter <ul><li>The following figure shows how to compute the (2,4) output pixel using these steps: </li></ul><ul><li>Rotate the convolution kernel 180 degrees about its center element. </li></ul><ul><li>Slide the center element of the convolution kernel so that it lies on top of the (2,4) element of A. </li></ul><ul><li>Multiply each weight in the rotated convolution kernel by the pixel of A underneath. </li></ul><ul><li>Sum the individual products from step 3. </li></ul>
  5. 5. Convolution Filter
  6. 6. Matlab Code <ul><li>Sample Code </li></ul><ul><li>I = imread('coins.png'); </li></ul><ul><li>h = ones(5,5) / 25; </li></ul><ul><li>I2 = imfilter(I,h); </li></ul><ul><li>imshow(I), title('Original Image'); </li></ul><ul><li>figure, imshow(I2), title('Filtered Image' </li></ul>
  7. 7. Example:- Use of Filter in a Line Follower
  8. 8. Cont..
  9. 9. Cont..
  10. 10. Result of Filtering
  11. 11. Modified Filter

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