Sustainability of Digital Formats: Planning for Library of Congress Collections

JPEG File Interchange Format Family (JFIF) is an image file format standard published as ITU-T recommendation T.871 and ISO/IEC 10918-5. JFIF defines a minimal container specification for image data encoded with the JPEG Image Encoding Family. In other words, JPEG file performs the encoding and JFIF wraps the JPEG encoding.

JFIF v1.02, introduced in 1992, is the most commonly used. Both versions 1.00 and 1.01 were available for less than one year before the release of 1.02. For more, see History and JPEG File Interchange Format, Version 1.02.

JFIF is entirely compatible with the standard JPEG interchange format with the only additional requirement is the mandatory presence of the APP0 (application) marker right after the SOI (start of image) marker.

The JFIF version is declared in the frame header: "you can identify a JFIF file by looking for the following sequence: X'FF', SOI, X'FF', APP0, [2 bytes to be skipped], "JFIF", X'00'".... in which "the most significant byte is used for major revisions, the least significant byte for minor revisions."

May be applied in initial-state picture creation; often used for middle- and final-state archiving or end-user delivery.

Version 1.02 is fully disclosed as an open standard.

Version 1.01 was open and available as a specification.

Version 1.00 was shared among a small group of industry representatives during the development and public release of Version 1.01.

See: JPEG File Interchange Format, Version 1.02.

Limited. JFIF defines itself with image dimensions and unit of measurement. Version 1.02 also defines thumbnail dimensions and unit of measurement.

Accessibility Features

Accessibility for still image content is often supported by the use of alt text when displayed on the web. The carriage of this data is typically not embedded in the file itself but rather in the HTML code. See W3C's Images Tutorial for the Web Accessibility Initiative.

See JPEG_DCT_BL and JPEG_DCT_EXT.

JFIF magic numbers follow the JPEG “Start of Image” (SOI) values “0xFFD8” with a JFIF application marker “APPO” (“0xFFEO” in hex) followed by the Length field and the JFIF byte identifier “0x4A46494600”. There is no formal header, these two sets of JGED and JFIF markers in combination act as a signature file header.

For more information, see “JPEG File Interchange Format File Format Summary” taken from the Encyclopedia of Graphics File Formats, 2nd Edition.

JPEG File Interchange Format 1.00. See https://www.nationalarchives.gov.uk/pronom/fmt/42

JPEG File Interchange Format 1.01. See https://www.nationalarchives.gov.uk/pronom/fmt/43

The JPEG bitstream stores 16-bit word values in big-endian format. JPEG data in general is stored as a stream of blocks, and each block is identified by a marker value. The first two bytes of every JPEG stream are the Start Of Image (SOI) marker values FFh D8h. In a JFIF-compliant file there is a JFIF APP0 (Application) marker, immediately following the SOI, which consists of the marker code values FFh E0h and the characters JFIF in the marker data, as described in the next section. In addition to the JFIF marker segment, there may be one or more optional JFIF extension marker segments, followed by the actual image data. For more, see JFIF, JPEG File Interchange Format, Version 1.02 and JPEG Image Encoding Family.

JFIF was developed by C-Cube Microsystems and Independent JPEG group. The creation is credited to Eric Hamilton at C-Cube Microsystems. After its creation, JFIF was placed in the public domain under the maintenance of Independent JPEG Group.

JFIF Version 1.00 was first released in 1991 among a small group of industry representatives. The first public release was Version 1.01 in 1992.

This format was initially released in 1991. Version 1.00 was shared among a small group of industry representatives during the development and public release of Version 1.01 in 1992. Version 1.02 was released shortly after and is “considered the de-facto standard”. All versions are backwards compatible.

According to Ecma TR-98, the differences between versions is relatively minor: Shortly after publication of v1.00, "the group came to the conclusion that the spatial sampling relationship of components specified in JFIF 1.0 was not ideal since it followed digital video conventions rather than those used in common computer formats such as Postscript and QuickTime. They chose to publish another version, JFIF 1.01, which changed that part of the specification to follow the computer format convention. This was deemed to be a minor change since JFIF 1.0 had been circulated for only a short while and decoders which ignored the version number would still render similar images. The Independent JPEG Group (IJG) adopted JFIF version 1.01 for use in its public domain software, which eventually led to millions of images being published in this format. Later in 1992, user feedback led to the final version of JFIF, version 1.02, which supported additional thumbnail formats – most importantly including thumbnails stored in compressed format.