AWARE SYSTEMS
TIFF and LibTiff Mail List Archive

Thread

2007.01.31 10:53 "[Tiff] Interpreting SubIFDs tag", by mikk
2007.01.31 17:23 "Re: [Tiff] Interpreting SubIFDs tag", by Joris
2007.02.01 09:42 "Re: [Tiff] Interpreting SubIFDs tag", by Gerben Vos
2007.02.01 18:32 "Re: [Tiff] Interpreting SubIFDs tag", by Joris
2007.01.31 19:24 "Re: [Tiff] Interpreting SubIFDs tag", by Phil Harvey
2007.01.31 19:54 "Re: [Tiff] Interpreting SubIFDs tag", by Joris
2007.01.31 22:24 "RE: [Tiff] Interpreting SubIFDs tag", by Grissom, Ed
2007.02.01 18:17 "RE: [Tiff] Interpreting SubIFDs tag", by Phil Harvey
2007.02.01 18:34 "Re: [Tiff] Interpreting SubIFDs tag", by Joris
2007.02.01 18:48 "Re: [Tiff] Interpreting SubIFDs tag", by Phil Harvey
2007.02.01 19:00 "Re: [Tiff] Interpreting SubIFDs tag", by Joris
2007.02.01 19:36 "Re: [Tiff] Interpreting SubIFDs tag", by Phil Harvey
2007.02.01 20:02 "Re: [Tiff] Interpreting SubIFDs tag", by Joris
2007.02.01 15:46 "Re: [Tiff] Interpreting SubIFDs tag", by Phil Harvey

2007.02.01 18:17 "RE: [Tiff] Interpreting SubIFDs tag", by Phil Harvey

Here is the document that invented the SubIFD concept -- this is the "Tiff Trees" approach. (http://partners.adobe.com/public/developer/en/tiff/TIFFPM6.pdf)

To quote this specification:

"If there is more than 1 child image for a given parent image, the NextIFD value of Child #1 must point to Child #2, and so on. The last Child’s NextIFD value must be zero."

I should point out that Adobe themselves don't store multiple SubIFD's like this.

The current version of the Adobe DNG converter writes multiple SubIFD's by storing a separate pointer for each in the SubIFD tag (and each SubIFD has a zero NextIFD pointer).

But this is definitely not the first time that Adobe has ignored their own specification.

- Phil