Tag Image File Format / Electronic Photography

"Tag Image File Format / Electronic Photography" (TIFF/EP) is a digital image file format standard – ISO 12234-2, titled "Electronic still-picture imaging – Removable memory – Part 2: TIFF/EP image data format". This is different from the Tagged Image File Format, which is a standard administered by Adobe currently called "TIFF, Revision 6.0 Final – June 3, 1992".

The TIFF/EP standard is based on a subset of the Adobe TIFF standard, and a subset of the JEITA Exif standard, with some differences and extensions.

One of the uses of TIFF/EP is as a raw image format. A characteristic of most digital cameras (but excluding those using the Foveon X3 sensor or similar, hence especially Sigma cameras) is that they use a color filter array (CFA). Software processing a raw image format for such a camera needs information about the configuration of the color filter array, so that the raw image can identify separate data from the individual sites of the sensor. Ideally this information is held within the raw image file itself, and TIFF/EP uses the tags that begin "CFA", CFARepeatPatternDim and CFAPattern, which are only relevant for raw images.

This standard has not been adopted by most camera manufacturers – DCF is the current industry standard file organisation system which uses the Exchangeable image file format. However, TIFF/EP provided a basis for the raw image formats of a number of cameras. One example is Nikon's NEF raw file format, which uses the tag TIFF/EPStandardID (with value 1.0.0.0).^[1] Adobe's DNG (Digital Negative) raw file format was based on TIFF/EP, and the DNG specification states "DNG ... is compatible with the TIFF-EP standard".^[2] Several cameras use DNG as their raw file format, so in that limited sense they use TIFF/EP too.^[3]

New Tags

The following new tags are defined in the TIFF/EP standard, all to be placed in the first TIFF Image File Directory (IFD)

Differences from TIFF and Exif

There are no major departures by the TIFF/EP standard from the TIFF standard, except that many of the TIFF tags are ignored.

The TIFF/EP standard does however have a few notable differences from the Exif standards:

• All tags used by TIFF/EP which are defined by the Exif standard to reside within the Exif Sub-IFD now reside directly under the first (main) TIFF IFD.

• The Exif IFD Sub-IFD, Interoperability Sub-IFD and the MakerNote Tag have all been omitted.

• Unlike the TIFF 6.0 standard, the TIFF/EP standard defines a method of dealing with thumbnail images. This however is different from the method that is used in the Exif standard.

• Several tags defined by the Exif standard have been re-defined in the TIFF/EP standard – see table below.

Timeline for development and revision

These dates are limited to those in publicly available sources:

See also

• International Organization for Standardization
• Tagged Image File Format
• Exchangeable image file format
• List of ISO standards
• DCF

References

• ISO 12234-2:2001 Electronic still-picture imaging – Removable memory – Part 2: TIFF/EP image data format

1. ^ Barry Pearson: What is in a raw file?
2. ^ Adobe: DNG 1.3.0.0 Specification (June 2009) (scroll down a bit)
3. ^ Barry Pearson: Products from Camera Manufacturers that use DNG in some way
4. ^ Link to a copy of the 1998 draft standard
5. ^ Link to a copy of the 2000 draft standard
6. ^ ISO: ISO 12234-2:2001
7. ^ I3A (International Imaging Industry Association): WG18, Ad Hoc groups and JWG 20/22/23 Meet in Tokyo
8. ^ Web archive of widely distributed email: Forwarded Message from a member of the ISO TC42 (technical committee for photography) working group 18 (electronic imaging) standards group
9. ^ DPReview: Adobe seeks International recognition for DNG
10. ^ NPES: Minutes of ISO/TC 130/WG2, 37th Meeting, see 14f
11. ^ I3A (International Imaging Industry Association): ISO 12234 Part 2 – TIFF/EP (scroll down a bit)
12. ^ NPES: Minutes of ISO/TC 130/WG2, 39th Meeting, see 14f

External links

• Link to a copy of the 1998 draft standard