The scribd paper link is broken but you can find it here: http://research.microsoft.com/en-us/um/people/kopf/pixelart/... . It's very interesting and definitely worth a read in my opinion. You've got to hand it to Microsoft, we've seen a lot of great papers come out of their research department in the last 15 years. Here is a video of the algorithm being applied to Super Mario that I found when I was looking for the paper: http://www.youtube.com/watch?v=o2Fd-4NzB0w