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The Joint Photographic Experts Group, also known by the acronym JPEG, is a technical committee which develops image standards. JPEG is also the name of the group's primary standard for image compression—JPEG compression is widely used for images on websites and is supported by most editors, browsers and image viewers. This standard is also used to compress and store images created by most scanners and digital cameras.
In the early 1980s, terminals and computers with graphics abilities were not very common. The International Organization for Standardization (ISO) created working groups to develop standards for photographic-quality displays. By the mid 1980s, ISO and the International Telegraph and Telephone Consultative Committee (CCITT) had released image coding standards. In 1986, the Joint Photographic Experts Group was formed from participants within ISO and CCITT. This committee went on to create several JPEG standards for the coding and compression of still images.
A related committee was formed in 1988 from the same ISO working group which created the Joint Photographic Experts Group. Known as the Joint Bi-Level Image Experts Group (JBIG), this committee focuses entirely on binary images. An image containing only two colors, such as black and white, is called a binary image. The JBIG committee is responsible for at least two standards regarding the lossless compression of binary images.
Most implementations of the original Joint Photographic Experts Group standards involve some degree of image quality loss. Generally, the more an image is compressed, the greater the loss of quality will be. This is known as lossy compression for this reason. Using a graphics editor to manipulate a JPEG image will usually cause further quality loss each time it is edited. The full JPEG standard includes lossless compression as well, but it is rarely implemented in web applications.
Several standards have been released by the Joint Photographic Experts Group since the original publications in the early 1990s. A standard called JPEG-LS was introduced in the late 1990s to improve the original lossless compression method. It also includes a standard for compression which falls between lossy and lossless. The JPEG 2000 standard redesigned the original compression method, increasing performance and flexibility. Introduced in 2009, the JPEG XR standard includes improvements to compression, color accuracy and transparency.
The standards of the Joint Photographic Experts Group are designed specifically for still pictures. In 1988, another ISO working group began to develop standards for the compression of video and audio. This committee became known as the Moving Picture Experts Group (MPEG). Its standards are widely used for streaming Internet video, high-definition digital television and Digital Video Disc (DVD) technology.
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