Palm bitmap

Palm bitmap, or Palm BitmapType (also called Palm Pilot Tbmp, Palm Pilot Bitmap, Palm pixmap, etc.), is a native bitmap format of Palm OS. It supports a variety of image types and compression schemes.

It can be found embedded in some Palm file formats, and apparently has also been used by itself as a file format. In a PRC file, resources named "Tbmp", "tAIB", and probably others, use this format.

Format details

There can be multiple images in a file. Each image begins with a header. In some cases the header is followed by a color table, or a "DirectInfoType" structure. The pixel data follows.

There are about four different versions of the bitmap format. This section summarizes the information in the Palm OS Reference (see the Links section below), and uses some terms defined there. It does not include every detail. "Same" means the field is the same as in the previous version. Different bitmap versions often appear in the same file.

Some newer-format bitmaps begin with an extra 16-byte "dummy" header, whose would-be pixelSize field is set to 0xff. This header must be skipped over to get to the real header.

Multi-byte numeric fields are normally big-endian. Little-endian variants of the format evidently exist, but are not covered here. For one thing, the documentation implies there is a V3 variant with version=0x83.

Header