I've also recently written and tiny-c-compiled several small utilities to convert framebuffer to conventional graphic formats - bmp, pgm, tiff and png (based on the LodePNG version 20120623 by Lode Vandevenne). These were succesfully tested on my K3 (4bpp), but unfortunately, I have no 8bpp raw images to play with... If someone could provide raw-8bpp-files made on K4 & K5, I would be very appreciated.
Just for testing purposes - screen2png
, that contains [i] c-code & compiled binary to make png-shots and store them in the /mnt/us/pictures/screenshots/ (so that Alt-Z allows you to see the made screenshots via the built-in picture viewer) and [ii] scripts to launch it from launchpad (Shift-Q-Q = instant shot, Shift-Q-W = shot after 10 seconds) & kite.
is the c-sources and compiled binaries to convert the framebuffer content to uncompressed bmp, pgm & tiff and, then, to compress them with the system call of bzip2. I expect that screen2pgm should properly work on 8bpp-devices.