TIFF Tag ExtraCameraProfiles
|Code||50933 (hex 0xC6F5)|
|Count||Number of extra camera profiles|
Used in IFD 0 of DNG files.
A list of file offsets to extra Camera Profile IFDs. The format of a camera profile begins with a 16-bit byte order mark (MM or II) followed by a 16-bit "magic" number equal to 0x4352 (CR), a 32-bit IFD offset, and then a standard TIFF format IFD. All offsets are relative to the start of the byte order mark. Note that the primary camera profile tags should be stored in IFD 0, and the ExtraCameraProfiles tag should only be used if there is more than one camera profile stored in the DNG file.
Note that in this tag the DNG specification breaks the TIFF specification. These Camera Profile IFDs are not well-formed IFDs, though they are functionally best approached as if they were, and as such this is not a tag with IFD pointer data similar to SubIFDs. Neither does this tag contain well-formed LONG data, because the tag data is not self-contained. As a result, this tag can easily corrupt output of TIFF-level editing software, and causes incompatibility between DNG and BigTIFF preventing DNG from growing beyond the 4 gigabyte maximum length boundary, etc...
If you have a need to extend any TIFF-based file format with child IFD types of your own, in any other context, we strongly suggest you use the IFD or IFD8 datatype to point to actual well-formed IFDs instead.