CCITT Group 4

CCITT Group 4 is a widely-used lossless compression algorithm for bitonal images. It is also known as T6, T.6, Fax4, G4, Group 4, or ITU-T Fax Group 4. It is frequently used in TIFF images created by scanning bitonal images.

It uses Modified Modified READ (MMR) compression. MMR is probably another synonym for CCITT Group 4.

Related formats
In a TIFF file, compression type 4 is CCITT Group 4.

Other formats that can use CCITT Group 4 compression include PDF and SPIFF.

Specifications

 * T.6 : Facsimile coding schemes and coding control functions for Group 4 facsimile apparatus

Software

 * Farbfeld Utilities
 * ImageMagick (specify the file format as "GROUP4")