@neauoire What's exciting to me about this kind of tool is the idea of doing this reduction, and maybe even mutating the original graphics a little to increase the number of duplicated tiles, and then somehow alter the "dictionary" image, like offset all the tile ids by one or something or replace a "dictionary" image from another image entirely, to get glitches in the mode of old NES mapper-page errors.
@mcc yes! I heading toward something that'll be like "Well, if there's only 1 pixel difference between these 2 tiles, merge them", but with a slider that let's me choose the losslessness.