ILBM
The Amiga's standard image format: an IFF-based raster format that stores bitplanes interleaved line by line.
ILBM (InterLeaved BitMap) is the image type the IFF standard defined for the Amiga in 1985. The file is a FORM ILBM with clearly named chunks: BMHD for size and depth, CMAP for the palette, and BODY for the picture itself, often packed with the simple ByteRun1 run-length scheme. The name refers to the bitplanes being stored interleaved one raster line at a time, exactly as the Amiga's hardware wants to read them.
The format became the de facto standard through Deluxe Paint and carried most of the scene's graphics, from hand-drawn logos to EHB and HAM images. A .lbm file still opens in modern tools — an unusually durable legacy of the 1980s.