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

Additional Excercises for Chapter 8

  1. Adaptive Thresholding
    Use Pixel Jelly to open each of the images below. For each image you should 1) convert the image to binary using a fixed global threshold of 128 2) convert to binary by adaptively selecting the global threshold and 3) convert to binary by selecting the threshold that you believe produces the best results. Compare each set of outputs. Discuss the differences that you detect visually and give your subjective preference as to whether the fixed threshold or the adaptive threshold produces the highest quality.

  2. Error Diffusion (Binary)
    Use Pixel Jelly to open open each of the images below. For each image you should convert it to binary using random thresholding, Floyd-Steinberg, Jarvis-Judice-Ninke, Stucki and Sierra dithering. Compare the results and give your subjective evaluation of the quality of each dithering technique.

  3. Error Diffusion (Color)
    Use Pixel Jelly to open open each of the images below. For each image you should dither it using a color palette containing only 5 colors: red, green, blue, black and white. Apply each of the Floyd-Steinberg, Jarvis-Judice-Ninke, Stucki and Sierra dithering techniques. Also, generate a color palette (using visual inspection and hand-selecting the colors) containing only 5 colors that you believe produces the best results. Experiment with 'zooming out' on each dithered image. Why the distortion?