JBIG

JBIG is an early lossless image compression standard from the Joint Bi-level Image Experts Group, standardized as ISO/IEC standard 11544 and as ITU-T recommendation T.82 in March 1993.[1] It is widely implemented in fax machines. Now that the newer bi-level image compression standard JBIG2 has been released, JBIG is also known as JBIG1. JBIG was designed for compression of binary images, particularly for faxes, but can also be used on other images. In most situations JBIG offers between a 20% and 50% increase in compression efficiency over the Fax Group 4 standard, and in some situations, it offers a 30-fold improvement.

This article is about the bi-level image compression scheme. For its designers, see Joint Bi-level Image Experts Group.
JBIG
Filename extension
.jbg, .jbig
Developed byISO, IEC, ITU-T
Initial release1993
Type of formatImage file formats
Extended toJBIG2
StandardsISO/IEC 11544, ITU-T Recommendations T.82, T.85

JBIG is based on a form of arithmetic coding developed by IBM (known as the Q-coder) that also uses a relatively minor refinement developed by Mitsubishi, resulting in what became known as the QM-coder. It bases the probability estimates for each encoded bit on the values of the previous bits and the values in previous lines of the picture. JBIG also supports progressive transmission, which generally incurs a small overhead in bit rate (around 5%).

Patents

Doubts about patent licence requirements for JBIG1 implementations by IBM, Mitsu­bishi and AT&T prevented the codec from being widely implemented in open-source software.[2] For example, as of 2012, none of the commonly used web browsers supported it. Since 2012, there are now no more JBIG1 patents in force – the last ones to expire were Mitsubishi's patents in Canada and Australia (on 25 February 2011) and in the United States (on 4 April 2012).[2][3]

gollark: ```RANGE SIZE STATE REMOVABLE BLOCK0x0000000000000000-0x000000008fffffff 2.3G online yes 0-170x0000000100000000-0x000000026fffffff 5.8G online yes 32-77```Weird.
gollark: Idea: bee (🇧) utterly apioform.
gollark: No idea. I use xscreensaver myself.
gollark: This is known to GTech™ apiarists, yes.
gollark: Actually, this doesn't exist.

See also

ISO/IEC JTC 1/SC 29

References
  1. Akramullah, Shahriar (2014). "Video Coding Standards". Digital Video Concepts, Methods, and Metrics. Apress. pp. 55–100. doi:10.1007/978-1-4302-6713-3_3. ISBN 978-1-4302-6712-6.
  2. JBIG1 patent information
  3. US5404140


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