SToyan Stefanov has posted some examples of what sort of output can be made with the imagefilter function in PHP.

Here’s the list of filters he applies:

  • Brightness
  • Grayscale
  • Contrast
  • Colorize
  • Edge Detect
  • Emboss
  • Gaussian Blur
  • Selective Blur
  • Mean Removal
  • Smooth
  • Negate

And, as a sort of a bonus, he includes a lazy way to make your image look like it’s sepia toned.