There is only one file type that uses the .LBM extension:
Deluxe Paint Bitmap Image
Interchange File Format-Interleaved Bitmap (IFF-ILBM) file; created by Electronic Arts' Deluxe Paint, a graphics editor developed for Amiga systems and later ported to other platforms.
LBM files use formatting similar to Portable Bitmap (.PBM) files. They may be black and white, 16 color, or 256 color images.
IFF-ILBM files are also seen with the .ILBM extension. Sometimes they are also stored as .IFF files.
Updated: September 21, 2008