2004.05.27 01:15 "[Tiff] large TIFF - two alternatives", by Steve Carlsen

2004.05.27 16:37 "Re: [Tiff] large TIFF - two alternatives", by Frank Warmerdam

Alternative 1: Minimal changes for TIFF to support 8-byte addresses

  1. ID = 43 (or maybe 0x4242?)
  2. 8-byte offset to 0th IFD
  3. Value/Offset fields are 8 bytes
  4. 8-byte offset to the next IFD (does anyone use this?)
  5. add TIFFType of LONG8, an 8 byte (unsigned) int
  6. StripOffsets and TileOffsets and ByteCounts can be LONG8


I think this approach is sensible and easy to implement. Any implementor of existing TIFF readers or writers could adapt to support this fairly easily.

I am not fond of Alternative 2 as an upgrade to TIFF since it substantially alters the TIFF data model which I think would be disruptive. Of course, it might make sense to pursue as a next-generation imaging format but I wouldn't really want to call it TIFF. I also doubt that it would have enough advantages to gain wide adoption but I could be wrong.

So, back to option 1, what would it take to get this ball rolling? Would Adobe consider producing an updated specification that addresses this? Would it be helpful for the libtiff team to go ahead with prototype implementation of the new format for "test driving"? I am personally very in favor of specification documents developed concurrently with a couple of interoperable implementations of the specification.

PS. Folks, sorry for not participating in the discussion much to date. I was off for a week when the discussion peaked and I never found much I felt I needed to add from skimming it all. Steve's Alternative 1 pretty much captures what I wanted to accomplish albeit at the cost that older readers can't possible get anything from the new files till updated.

Best regards,

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