Evolving the Mona Lisa

I'm attempting to recreate the project shown here, using perl and GD: http://rogeralsing.com/2008/12/07/ge...-of-mona-lisa/

Here is a link to my code: http://pastebin.com/nsDJ4rL5

I'm trying to find ways to speed the code up, the slowest function is score_images(), as it has to do a pixel by pixel comparison for multiple images.

Any ideas on how to speed up the script would be really appreciated :)

I was thinking of maybe rewriting this in C, I'm not sure how hard that would be though :\

Thank You