GrayPaint

GrayPaint is, we have to tell you, an exceedingly difficult format to Google for (or search for in any other search engine competing with Google&reg;). You end up with listings (native and paid) for various physical paint companies advertising the gray-scaled varieties of their products, and attempts to refine the search eventually get you to treatises on doing gray-scaled images in various computerized paint programs, as well as a conversion program in Visual Basic that happens to be called "Graypaint", but only converts established image file formats rather than inventing its own.

However, some more intense sleuthing does eventually disclose that there was an actual distinct program called GrayPaint with its own image format. It's for PalmOS devices, and the format (a grayscale raster graphic format) is a variety of the PalmOS Database (PDB) format, as are most things in PalmOS. A little bit of online documentation can be found on it, as well as mention of various graphic programs that claim to be able to load or convert this format.

Links

 * GrayPaint 2.2.3 documentation in plain text
 * Lemke GraphicConverter 9 claims to be able to import this format.