JBIG
Overview
Lossless data compression
Lossless data compression is a class of data compression algorithms that allows the exact original data to be reconstructed from the compressed data. The term lossless is in contrast to lossy data compression, which only allows an approximation of the original data to be reconstructed, in exchange...
image compression
Image compression
The objective of image compression is to reduce irrelevance and redundancy of the image data in order to be able to store or transmit data in an efficient form.- Lossy and lossless compression :...
standard from the Joint Bi-level Image Experts Group
Joint Bi-level Image Experts Group
The Joint Bi-level Image Experts Group is a group of experts nominated by national standards bodies and major companies to work to produce standards for bi-level image coding. The 'joint' refers to its status as a committee working on both ISO and ITU-T standards...
, standardized as ISO
International Organization for Standardization
The International Organization for Standardization , widely known as ISO, is an international standard-setting body composed of representatives from various national standards organizations. Founded on February 23, 1947, the organization promulgates worldwide proprietary, industrial and commercial...
/IEC
International Electrotechnical Commission
The International Electrotechnical Commission is a non-profit, non-governmental international standards organization that prepares and publishes International Standards for all electrical, electronic and related technologies – collectively known as "electrotechnology"...
standard 11544 and as ITU-T
ITU-T
The ITU Telecommunication Standardization Sector is one of the three sectors of the International Telecommunication Union ; it coordinates standards for telecommunications....
recommendation T.82. It is widely implemented in fax machines. Now that the newer bi-level image
Binary image
A binary image is a digital image that has only two possible values for each pixel. Typically the two colors used for a binary image are black and white though any two colors can be used. The color used for the object in the image is the foreground color while the rest of the image is the...
compression standard JBIG2
JBIG2
JBIG2 is an image compression standard for bi-level images, developed by the Joint Bi-level Image Experts Group. It is suitable for both lossless and lossy compression...
has been released, JBIG is also known as JBIG1. JBIG was designed for compression of binary images, particularly for fax
Fax
Fax , sometimes called telecopying, is the telephonic transmission of scanned printed material , normally to a telephone number connected to a printer or other output device...
es, 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.
JBIG is based on a form of arithmetic coding
Arithmetic coding
Arithmetic coding is a form of variable-length entropy encoding used in lossless data compression. Normally, a string of characters such as the words "hello there" is represented using a fixed number of bits per character, as in the ASCII code...
patented by IBM
IBM
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
, known as the Q-coder, but using a minor tweak patented by Mitsubishi
Mitsubishi
The Mitsubishi Group , Mitsubishi Group of Companies, or Mitsubishi Companies is a Japanese multinational conglomerate company that consists of a range of autonomous businesses which share the Mitsubishi brand, trademark and legacy...
, resulting in what became known as the QM-coder.
