Install gimptool-2.0 to compile and install /src/file_ilbm.c which implements a GIMP 2.10 loader plugin using the include src/libilbm.c ILBM parser library. gimptool-2.0 is available in most if not all package managers that also provide GIMP itself.
On Debian/Ubuntu/Mint install it by running:
sudo apt-get install libgimp2.0-dev
gimptool-2.0 --install src/file-ilbm.c
There is also a Makefile with basic build support.
The included libilbm library only supports basic core features of the image file ILBM standard. It supports color palettes but not real color bitmaps. It only supports masking by color not by plane.
It does however support basic heuristics to supported ILBM formatted images that were customized by the creators with non-standard chunk names.
Many commercial software developers used ILBM images in their products, especially early Amiga and DOS game developers who internally used Deluxe Paint 2 in their art department. To obfuscate the fact and maybe discourage easy modding, they changed standardized chunk identifiers from FORM or IMHD to something more custom.
When it detects a valid chunk structure in a file but the chunk identifiers do not match up with the standard, libilbm will try to make educated guesses to determine the chunks' functions. Hopefully it works around the obfuscation and arrives at a workable interpretation and successfully parse and load the image content.
The GIMP plugin supports detection of standardized ILBM and some obfuscated variants, using GIMP's magic load handler to support files without .ilbm extensions.
The magic loader is limited to the official magic identifier and a few known obfuscated magic identifiers. To make sure that GIMP will use libilbm to open an unknown file add an .ilbm file extension to the image file.
The library was development against and tested with the following source ILBM images.
- New ILBM images created with the DOS version of Deluxe Paint 2
- Non-obfuscated images found in the
GRAPHICSdirectory of Austrian game studio NEO's The Clue - Obfuscated images in the
GFXdirectory in the later NEO games Whale's Voyage and Whale's Voyage 2
- "EA IFF 85" Standard for Interchange Format Files - Original Electronic Arts standard definition
- Interleaved Bitmap (ILBM) - wikipedia.org