There seems to be several methods out there for reducing the colors in an image. I became interested in this after pondering how this is done in the excellent freeware program IrfanView. Unfortunately, their method is not described anywhere that I could find, but I imagine that it is something along the tree data structure collapse method that ImageMagick employes.
The biOps package employes the k-means clustering to arrive at a reduced number of colors. I find that while this method takes a bit longer, the results can actually look a lot better. Just for kicks, I imbedded the imgKMeans() function in another function called warholize() that replaces these reduced color levels with another set. It's definitly not a Warhol, but I still like the effect.
the function...
