Base image could be a combination of all the images

[spillerrec]

It is most commonly noticed with eyebrows:

The eyebrow moves, and the overlay image contains both erases the old eyebrow and paints the new one. Total size: 33,454 bytes

An alternative way would be to use a base image which contains no eyebrows, and two overlays just adding the eyebrows:

Total size: 33,046 bytes

Since the base image is simpler now, it got reduced with 458 bytes (from 30,068 bytes).
The two diff images are however larger by 50 bytes, but this can be removed by storing them in the same image like this:

It is now smaller with 64 bytes, thus smaller than the original diff image as well. Worth doing this for 64 bytes? Probably not, but something to think about nevertheless.

	Current	Proposed	Shared context
Base	30,068	29,610	29,610
Diff 1		1,572
Diff 2	3,386	1,864	3,372
Total	33,454	33,046	32,982