then they can't use it. I have a corrupted version of WinRAR and the trial on it refuses to run out. Every time I open it: 'You have 40 days trial period remaining.' It's _always_ 40. Anyway, that's very useful for me.
I've been thinking of something like this. Publicly available libraries will be able to deal with decompression and compression of all files involved. One could determine the closest element colour by using parallel arrays, on for the element, another for the color of each element. Then using subtracting the color values of the elements from the color values of the current pixel of the image(or something along those lines) you can get the element that most closely resembles the colour in the image. Then just resave in the format of a stamp, which as I remember is quite simple.