JPEG
Joint Photographic Experts Group created the dominant image compression standard in 1992.
JPEG, short for Joint Photographic Experts Group (and sometimes called JPEG 1 retroactively), is a widely used method for compressing digital images with some loss of data, especially those from digital cameras. The amount of compression can be adjusted, letting users choose between smaller file sizes and better image quality. At a typical 10:1 compression ratio, the quality loss is noticeable but generally considered acceptable. First released in 1992, JPEG became the world’s most popular image compression standard and digital image format, with billions of JPEG files created daily by 2015.
The Joint Photographic Experts Group, formed in 1986, published the JPEG standard in 1992. It relies on the discrete cosine transform (DCT) algorithm, first proposed as an image compression technique by Nasir Ahmed in 1972 and detailed in a 1974 paper by Ahmed, T. Natarajan, and K. R. Rao. The standard also cites patents from IBM, Mitsubishi Electric, AT&T, and Canon Inc., which cover its arithmetic coding methods. Notably, a 1986 patent by Wen-Hsiung Chen and Daniel J. Klenke, later owned by Forgent Networks, sparked controversy in 2002 when Forgent claimed it covered JPEG technology. The JPEG committee and many experts considered the patent invalid due to prior art.
JPEG’s success helped drive the spread of digital images and photos online and on social media. The compression method appears in several file formats. JPEG/Exif is the most common format in digital cameras, while JPEG/JFIF is standard for storing and sharing photos on the web; these are often simply called JPEG. The MIME type is "image/jpeg," though older Internet Explorer versions used "image/pjpeg" for uploads. File extensions are typically ".jpg" or ".jpeg." JPEG/JFIF supports images up to 65,535×65,535 pixels, or up to 4 gigapixels at a 1:1 aspect ratio. In 2000, the JPEG group introduced JPEG 2000 as a successor, but it never replaced the original as the dominant standard.
The JPEG standard itself defines the codec—how an image is compressed into bytes and decompressed—but not the file format. Exif and JFIF provide the common interchange formats. The official name is "Information technology – Digital compression and coding of continuous-tone still images," with ISO/IEC 10918 covering multiple parts. Ecma International TR/98, first published in June 2009, specifies the JPEG File Interchange Format (
- full_name
- Joint Photographic Experts Group (JPEG)
- year_created
- 1992
- field
- Image compression
- known_for
- Lossy compression for digital images, discrete cosine transform (DCT) algorithm
- mime_type
- image/jpeg
- max_image_size
- 65,535×65,535 pixels (up to 4 gigapixels at 1:1 aspect ratio)
Lore & Background
The Joint Photographic Experts Group created the JPEG standard in 1992, based on the discrete cosine transform (DCT) algorithm first proposed by Nasir Ahmed as an image compression technique in 1972. The group was founded in 1986, with the 'Joint' standing for ISO TC97 WG8 and CCITT SGVIII. The JPEG standard was published in 1992 and approved in September 1992 as ITU-T Recommendation T.81, and in 1994 as ISO/IEC 10918-1.
JPEG was largely responsible for the proliferation of digital images and digital photos across the Internet and later social media. JPEG compression is used in a number of image file formats, with JPEG/Exif being the most common format used by digital cameras and JPEG/JFIF being the most common for storing and transmitting photographic images on the World Wide Web. The JPEG specification cites patents from several companies, including IBM, Mitsubishi Electric, AT&T, and Canon Inc.
In 2002, Forgent Networks asserted patent rights on JPEG technology based on U.S. patent 4,698,672 filed by Compression Labs' Wen-Hsiung Chen and Daniel J. Klenke. The JPEG committee investigated and believed the patent was invalidated by prior art. After legal battles, the USPTO found the patent invalid in May 2006 based on prior art, and Forgent agreed to abandon enforcement in November 2006.
Reader's Guide
JPEG's significance lies in its role as the most widely used image compression standard globally, enabling the explosion of digital photography and image sharing on the Internet and social media. Its lossy compression algorithm, based on the discrete cosine transform, allows adjustable trade-offs between storage size and image quality, typically achieving 10:1 compression with perceptible but acceptable quality loss. The format's ubiquity is reflected in its support across virtually all digital cameras, web browsers, and image software. The JPEG standard specifies the codec for compression and decompression but not the file format; the Exif and JFIF standards define the commonly used interchange formats. Despite the introduction of a successor, JPEG 2000, in 2000, the original JPEG has remained dominant. The patent controversies surrounding JPEG, particularly Forgent's claims and subsequent invalidation, highlight ongoing tensions between proprietary patents and open standards. The JPEG committee's explicit goal of ensuring baseline methods are implementable without license fees has contributed to the format's widespread adoption.
Did You Know?
- JPEG typically achieves 10:1 compression with a loss in image quality that is widely agreed upon to be acceptable.
- The JPEG specification cites patents from IBM, Mitsubishi Electric, AT&T, and Canon Inc.
- In 2006, the USPTO found Forgent's JPEG patent invalid based on prior art, and Forgent knew about the prior art but intentionally avoided telling the Patent Office.
- JPEG/JFIF supports a maximum image size of 65,535×65,535 pixels, up to 4 gigapixels for an aspect ratio of 1:1.
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