23 Facts About JPEG

JPEG is a commonly used method of lossy compression for digital images, particularly for those images produced by digital photography.

JPEG typically achieves 10:1 compression with little perceptible loss in image quality.

Since its introduction in 1992, JPEG has been the most widely used image compression standard in the world, and the most widely used digital image format, with several billion JPEG images produced every day as of 2015.

Term "JPEG" is an acronym for the Joint Photographic Experts Group, which created the standard in 1992.

JPEG was largely responsible for the proliferation of digital images and digital photos across the Internet, and later social media.

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JPEG compression is used in a number of image file formats.

Original JPEG specification published in 1992 implements processes from various earlier research papers and patents cited by the CCITT and Joint Photographic Experts Group.

However, the JPEG specification did cite two earlier research papers by Wen-Hsiung Chen, published in 1977 and 1984.

JPEG standard specifies the codec, which defines how an image is compressed into a stream of bytes and decompressed back into an image, but not the file format used to contain that stream.

JPEG committee investigated the patent claims in 2002 and were of the opinion that they were invalidated by prior art, a view shared by various experts.

JPEG committee has as one of its explicit goals that their standards be implementable without payment of license fees, and they have secured appropriate license rights for their JPEG 2000 standard from over 20 large organizations.

However, JPEG is not well suited for line drawings and other textual or iconic graphics, where the sharp contrasts between adjacent pixels can cause noticeable artifacts.

The JPEG standard includes a lossless coding mode, but that mode is not supported in most products.

JPEG uses a lossy form of compression based on the discrete cosine transform .

Several alterations to a JPEG image can be performed losslessly as long as the image size is a multiple of 1 MCU block .

JPEG File Interchange Format is a minimal file format which enables JPEG bitstreams to be exchanged between a wide variety of platforms and applications.

Image files that employ JPEG compression are commonly called "JPEG files", and are stored in variants of the JIF image format.

In practice, most JPEG files contain a JFIF marker segment that precedes the Exif header.

Many of the options in the JPEG standard are not commonly used, and as mentioned above, most image software uses the simpler JFIF format when creating a JPEG file, which among other things specifies the encoding method.

JPEG standard allows, but does not require, decoders to support the use of arithmetic coding, which is mathematically superior to Huffman coding.

Some standard but rarely used options already exist in JPEG to improve the efficiency of coding DCT coefficients: the arithmetic coding option, and the progressive coding option .

JPEG XT was published in June 2015; it extends base JPEG format with support for higher integer bit depths, high dynamic range imaging and floating-point coding, lossless coding, and alpha channel coding.

The standard is expected to exceed the still image compression performance shown by HEVC HM, Daala and WebP, and unlike previous efforts attempting to replace JPEG, to provide lossless more efficient recompression transport and storage option for traditional JPEG images.