HP 100LX/200LX icon

The HP 100LX and HP 200LX palmtop computers used a custom icon format, with filename extension .ICN.

Format
We did not find much documentation about this format, but the examples we've seen use a simple uncompressed bi-level format, with an 8-byte header. The image dimensions are stored in the header, but they are probably always 44×32.

Identification
A file begins with bytes.

Assuming dimensions of 44×32 pixels, the next four bytes are, and the file is exactly 200 bytes in size.

Format details
[This information is based on analysis of a small number of files, and may be incorrect.]

Multi-byte integers are little-endian.

Sample files

 * http://cd.textfiles.com/20mnn/PALMTOP/WINICO.ZIP
 * Themes for the X-Finder GUI on the HP 200LX Palmtop PC

Links

 * Wikipedia: HP 200LX
 * https://telparia.com/fileFormatSamples/image/hpPalmtopIcon/

Editors' notes
The packages at the "Themes for the X-Finder GUI" site listed above also contain some .XBG files, which use the same format as .ICN, but are larger in image size, and are intended to be used as wallpaper/background images instead of icons. We haven't found any other information about XBG files, but this suggests that ICN may just be a subformat of some other format.