I'm currently making a gallery of screeshots of a flash game.
The files save rather well in truecolor png format, but looking at the files color histogram using imagemagick's identify -verbose, I realized that all of them have betweenn 100 and 500 distinct colors , making paletted choices better in term of file size. (most colors are almost never represented, and are due to antialliassing)

Those under 257 colors are better stored as palette pngs, but I'd like to try to save the others as two layers animated gifs, with no delay between the two frames.
The idea is to put all the most represented pixels of the histogram in the first frame, and replace the not yet displayed pixels by the color of nearest already set pixel, then in the second frame display the rest, with most of the image's second frame being transparent.

I'm used to perl, but never tried PerlMagick yet.
Any advice about how to start towards my aim ?