Description:

jbig2dec is a decoder implementation of the JBIG2 image compression
format. JBIG2 is designed for lossy or lossless encoding of 'bilevel'
(1-bit monochrome) images at moderately high resolution, and in
particular scanned paper documents. In this domain it is very
efficient, offering compression ratios on the order of 100:1.

This is a decoder only implementation, and currently is in the alpha
stage, meaning it doesn't completely work yet. However, we are
maintaining parity with available encoders, so it is useful for real
work.

The specificication has been published as ISO IEC 14492 and ITU T.88.
These documents completely describe the format and they'll be required
if you want to understand the code and contribute. We prefer the ISO
version, but haven't discovered significant differences between the
two.

JBIG2 also includes the CCITT T.4 and T.6 (group 3 and group 4) fax
encodings, which are documented separately. Their specifications and
T.88 can be obtained from the ITU. The ISO version of JBIG2 can be
obtained through the ISO website.