Digital Negative - Standardization

Standardization

DNG is not (yet) a standard format, but is based on several open formats and/or standards and is currently being used by ISO in its revision of TIFF/EP. Here is a summary of the timeline:

• 2001: The ISO standard raw image format, ISO 12234-2, better known as TIFF/EP, was ratified and published. (TIFF/EP also supports "non-raw", or "processed", images). TIFF/EP provided a basis for the raw image formats of a number of cameras, but they typically added their own proprietary data. Some cameras have sensors that cannot be described by the current version of TIFF/EP.
• 2004, September: Adobe launched DNG based on TIFF/EP. (The DNG specification states "DNG ... is compatible with the TIFF-EP standard"). DNG is an extension of TIFF/EP with considerably more specified metadata. In effect, DNG was TIFF/EP brought up-to-date and made fit for purpose. DNG also exploits various other open formats and/or standards, including Exif metadata, XMP metadata, IPTC metadata, CIE XYZ coordinates, ICC profiles, and JPEG. Although DNG supports more sensor configurations than TIFF/EP, (for example, cameras from Fujifilm using Super CCD sensors), it still doesn't support all sensor types as raw images, especially those using the Foveon X3 sensor or similar, hence especially Sigma cameras.
• 2006: TIFF/EP began its 5-year revision cycle.
• 2006 to 2007 sometime: Adobe offered the DNG specification to ISO to be part of ISO's revised TIFF/EP standard.
• 2008, September & October: Minutes of ISO/TC 130/WG2 — Prepress Data Exchange, 37th Meeting: "WG 18 is revising the two-part standard (ISO 12234), which addresses digital camera removable memory. The revision of ... Part 2 will add DNG into TIFF/EP." A progress report from ISO about the revision of TIFF/EP stated that the revision "... currently includes two "interoperability-profiles," "IP 1" for processed image data, using ".TIF" extension, and "IP 2" for "raw" image data, ".DNG" extension".
• 2009, September: Minutes of ISO/TC 130/WG2 — Prepress Data Exchange, 39th Meeting: the revision of TIFF/EP "is comprehensive to support many different use cases, including backward compatibility with current TIFF readers and support of Adobe DNG.... Profile 2 (proposed extension .dng, if Adobe is in agreement) is intended for camera raw images, including un-demosaiced images.... This format will be similar to DNG 1.3, which serves as the starting point for development."
• Future?: If ISO's revision of TIFF/EP continues as it has been doing, (this is not guaranteed), there will be an ISO Standard with one of its interoperability profiles based on DNG version 1.3 and used with the file extension ".DNG" or ".dng".