2007.01.31 19:24 "Re: [Tiff] Interpreting SubIFDs tag", by Phil Harvey
I just scanned my set of test images. Unfortunately I don't have a sample where the next IFD pointer is used in the SubIFD. However, I did note there are a number of images where the next IFD pointer is not even written for Interop and Exif IFD's (ie. not zero but not meaningful either). So it looks like one should ignore the next IFD pointer for these IFD's.
So my question is: For what IFD's is the next-IFD pointer meaningful? (IFD0 obviously, SubIFD apparently, but what is the official word on Interop and Exif IFD's, and what about GlobParam and GPS IFD's?)