The Art of Digital Image Processing
© Kenny Hunt, hunt.kenn@uwlax.edu

Additional Excercises for Chapter 7

  1. Interpolation and Affine Transforms
    Use Pixel Jelly to open each of the image files below. For each image you should rotate the image by 30 and 45 degrees using both forward an reverse mapping using both nearest neighbor and bilinear interoplation. You should thus generate eight destination images for each of the source images below. Discuss your results specially addressing the question of whether or not a forward mapped rotation followed by median filtering is comparable to the use of backward mapping with high-order interpolation (bilinear or bicubic for example).

  2. Affine Transforms
    Use Pixel Jelly to open open the image below. Determine the affine transformation matrix required for a horizontal shear of 1.2, a vertical shear of 1.4 and the transformation that applies both of these shears simultaneously. Is a horizontal shear of 1.2 followed by a vertical shear of 1.4 identical to a vertical shear of 1.4 followed by a horizontal shear of 1.2? Is a horiztonal shear of 1.2 followed by a vertical shear of 1.4 identical to application of those shears simultaneously?

  3. Geometric Distortions
    Use Pixel Jelly to take the source image below and construct the destination image shown. Describe how a kaleidoscope mapper could be implemented.