>I thought you were using something like a low (2,3,4) bit
>PNG with a cmap.

No it's a 2-bit greyscale mapping, 4 bits per byte. This is the most efficient overall to use, too, since no bits are wasted.

Other formats would increase the filesize by at least 2X or 4X, and really save any CPU, since most PNG overhead is directly proportional to the file size (bytewise checksum, and CRC32, and ..).

Good thought, though.

There's also a RAW (twice the size) screen file in /proc, which is very low overhead, for app's that want it.

-ml