2005.05.27 03:03 "[Tiff] Support for NewSubFileType by various TIFF Specifications", by Bob Young
I’m in the process of adding thumbnail images to TIFF files of our digital camera firmware. Due to the fact that some of the TIFF module’s functions are shared by other objects such as EXIF and DNG, and the fact that I can’t guarantee I’ll be decoding files that I’ve written, I need to support four different TIFF related specifications: TIFF/EXIF (ver 2.2), TIFF6.0, TIFF/EP, and DNG.
I need to sort out the thumbnail, if any, location, (IFD0, IFD1, or a SubIFD of IFD0) when decoding a file conforming to any one of the four specs. My question is, in any TIFF file conforming to one of those four, can I rely on each IFD and/or SubIFD containing either a NewSubFileType or a SubFileType tag?