CS 7321 Winter 1998 PS #2 Solutions by Joe Bayes

Problem #2

I had some problems understanding exactly what was done to create each image, but I think I got most of them done right.

The two biggest problems I had with this assignment were getting matlab to print out the images using the right colormap (and realizing that the problem was the colormap in the first place), and getting netscape to reload images when I had changed the images (again, and recognizing that that was the problem.

• Original Image
  

• Filtered with frod=medfilt2(rod);
  

• Gradient using 1x2 and 2x1 masks (filtered):
  
• Gradient using 1x2 and 2x1 masks (filtered), T=32:
  
• Gradient using 2x2 masks (filtered)
  
• Gradient using 2x2 masks (filtered), T=64
  
• Roberts Cross (filtered)
  I can't figure out how to get the "edge" operator to spit out a greyscale image, so for the Roberts Cross, Sobel, and Prewitt operators I'm just showing you the black and white image.
  
• Sobel (filtered)
  
• Prewitt (filtered)
  
• Gradient using 1x2 and 2x1 masks (unfiltered):
  
• Gradient using 1x2 and 2x1 masks (unfiltered), T=32:
  
• Gradient using 2x2 masks (unfiltered)
  
• Gradient using 2x2 masks (unfiltered), T=64
  
• Roberts Cross (unfiltered)
  
• Sobel (unfiltered)
  
• Prewitt (unfiltered)
  

Now, here's the same thing, when we introduce noise:

• Original (noisy) Image
  

• Filtered with frod=medfilt2(rod);
  

• Gradient using 1x2 and 2x1 masks (filtered):
  
• Gradient using 1x2 and 2x1 masks (filtered), T=32:
  
• Gradient using 2x2 masks (filtered)
  
• Gradient using 2x2 masks (filtered), T=64
  
• Roberts Cross (filtered)
  I can't figure out how to get the "edge" operator to spit out a greyscale image, so for the Roberts Cross, Sobel, and Prewitt operators I'm just showing you the black and white image.
  
• Sobel (filtered)
  
• Prewitt (filtered)
  
• Gradient using 1x2 and 2x1 masks (unfiltered):
  
• Gradient using 1x2 and 2x1 masks (unfiltered), T=32:
  
• Gradient using 2x2 masks (unfiltered)
  
• Gradient using 2x2 masks (unfiltered), T=64
  
• Roberts Cross (unfiltered)
  
• Sobel (unfiltered)
  
• Prewitt (unfiltered)
  

ps2.m: Here's the source code.