We know we’ve got to reduce the Swamp Talk app size to under the magic 20Meg mark, so that people will be able to download it over phone networks. One angle is to optimize the visual assets. We factored the lilypad out of all our frog frames, which reduced each individual frame by 35%. Imagine our surprise when we built the sprite sheet file (a single file that combines all the frames in a sequence) and got almost no reduction in file size. Uh-oh: we were really counting on saving some substantial file size here! Eventually we figured out that file size is surprisingly dependent on frog layout. We got our 35% by arranging the frogs wide instead of narrow, using Zwoptex’s “shelf” algorithm.
Naïvely, I would have expected .png compression to reduce essentially the same pixel data to the same size. But apparently it’s quite orientation-sensitive.