Exif Exchangeable Image File Format, Version 2.2

The Exchangeable Image File Format (Exif) specifications define a pair of file types, mainly intended for recording technical details associated with digital photography. The two types employ different image encodings based on existing image formats and the resulting files can be read by many image software applications. The Exif metadata shared by the two file types represents an extension to each of the underlying types.

Uncompressed files are recorded in TIFF Rev. 6.0 (TIFF_6) format, with an extended set of tags; see Tags for TIFF and Related Specifications. Compressed Exif files are recorded as baseline JPEG (ISO/IEC 10918-1) with metadata-containing application marker segments (APP1 and APP2) inserted.

The extended metadata defined by Exif is subsumed within the TIFF/EP specification; thus TIFF/EP can be seen as a successor-replacement to TIFF_UNC_EXIF.

Exif 2.2, also termed Exif Print, introduced tags to record camera settings, including scene type (portrait, landscape, night scene, etc.), that can be used to guide automatic adjustments before printing in order to best match the photographer's intent. The key difference between Exif 2.21 and Exif 2.2 is support for the Adobe RGB color space without embedding a color profile. In version Exif 2.2, the default color space is sRGB.

The Exif specification also provides a method for recording thumbnails and allows for the inclusion of audio in the WAVE format, to support such elements as photographers' spoken annotations.

See TIFF and JPEG_EXIF

See TIFF and JPEG_EXIF

See TIFF and JPEG_EXIF

From the specification:"Image data employs following existing image formats, depending on the image data type:

• RGB uncompressed data: Baseline TIFF Rev. 6.0 RGB Full Color Images,
• YCbCr uncompressed data: TIFF Rev. 6.0 Extensions YCbCr Images,
• JPEG compressed data: JPEG Baseline ADCT." (page 8)

"The combination of pixel composition and pixel sampling for image data shall be RGB 4:4:4 and either Y:Cb:Cr =4:2:2 or Y:Cb:Cr = 4:2:0. The pixel composition of image data shall also be 8 bits each. This specification is applied similarly to thumbnails. As sampling points on the elements making up pixels, the Y and Cb,Cr sampling points may be either co-sited or centered. . . . In the case of Y:Cb:Cr = 4:2:2, spatial co-siting is recommended for the sake of improved image quality on TV systems. For Y:Cb:Cr = 4:2:0, spatial centering is recommended as per the TIFF default and is most common format of the personal computer applications." (page 5)

Exif Version 2.2 was published in April 2002. See EXIF_Family for a full version publication timeline.

About JEITA: "The Japan Electronics and Information Technology Industries Association (JEITA) was formed on November 1, 2000, through the merger of the Electronic Industries Association of Japan (EIAJ) and Japan Electronic Industries Development Association (JEIDA). JEITA is a new industry organization in Japan with activities covering both the electronics and information technology (IT) fields." (http://www.jeita.or.jp/english/about/what/).

About CIPA: The Camera and Imaging Products Association (CIPA) was established in 2002 as a successor organization to the Japan Camera Industry Association (JCIA). JCIA participated in the original development of Exif. CIPA "is an industry association consisting of companies engaged in the development, production, or distribution of digital cameras, imaging-related products, and software" (http://www.cipa.jp/guide/documents/e/en0203.pdf).