Abbreviation for the Joint Photographic Experts Group
An image compression algorithm specified in ISO 10918-4.
The current version is JPEG2000.
It provides lossless and lossy compression, sequential and progressive compression, the choice of arithmetic or Huffman codes, and many other factors to optimize compression for classes of images and usage. It is designed as the standard for compression in the Group 3 Color Facsimile.
Filename extensions are .jpg and .jpeg.
Grayscale or 24-bit color (16.77 million colors).
Data is greatly compressed by omitting minor color changes in the image and extracting large color changes. (This takes advantage of the fact that it is more difficult to notice minor changes in color than changes in brightness.)
It also supports lossless compression; however, lossy compression is common. A wide range of compression, from a fraction of the original size to 1/100 of the original size, is possible; however, the greater the compression ratio, the greater the degradation of image quality.
It is suitable for the compression of images with smooth gradations and colors, such as natural images and photographs.
Standard: JIS X 4302 (ISO/IEC 10918, ITU-T T.81)