This Recommendation | International Standard defines methods for coding bi-level images and sets of images (documents consisting of multiple pages). It is particularly suitable for bi-level images consisting of text and dithered (halftone) data.

The methods defined permit lossless (bit-preserving) coding, lossy coding, and progressive coding. In progressive coding, the first image is lossy; subsequent images may be lossy or lossless.

This Recommendation | International Standard also defines file formats to enclose the coded bi-level image data.