ILBM

File Format
Name	ILBM
Ontology	Electronic File Formats Graphics ILBM
Extension(s)	.iff .lbm .ilbm
PRONOM	fmt/338

Overview

ILBM (or IFF-ILBM, or LBM) is a raster image file format, based on the IFF container format. ILBM stands for InterLeaved BitMap.

Identification

The ASCII strings "FORM", "ILBM", and "BMHD" appear near the beginning of the file.

Special types of ILBM

HAM

HAM images are designed to work with the Amiga's Hold-And-Modify display mode. HAM files should contain a "CAMG" chunk with a particular flag set. Images have a maximum of 4096 colors.

HAM8

HAM8 is a variant of HAM, designed to work with a display mode available on some Amigas. Images have a maximum of 262,144 colors.

HALFBRITE

HAM images are designed to work with the Amiga's Halfbrite display mode. HALFBRITE files should contain a "CAMG" chunk with a particular flag set. Images have a maximum of 64 colors.

See also

• IFF-PBM (Planar BitMap)

Software

• Netpbm
• XnView

Sample files

• ftp://ftp.back2roots.org/pub/amigascne/Gfx/pics/

Resources

• Wikipedia: ILBM
• ModdingWiki article
• Intro to Amiga IFF ILBM Files and Amiga Viewmodes
• IFF File Format Summary
• Wikipedia: Hold-And-Modify
• Wikipedia: Amiga Halfbrite mode