AWARE SYSTEMS
TIFF and LibTiff Mail List Archive

Thread

2004.09.01 20:39 "[Tiff] Stacked tiffs with colourmaps", by David Scriven
2004.09.02 01:27 "Re: [Tiff] Stacked tiffs with colourmaps", by Joris
2004.09.02 01:44 "Re: [Tiff] Stacked tiffs with colourmaps", by Chris Cox
2004.09.02 16:22 "Re: [Tiff] Stacked tiffs with colourmaps", by Ross A. Finlayson
2004.09.02 17:08 "Re: [Tiff] Stacked tiffs with colourmaps", by Bob Friesenhahn
2004.09.02 18:12 "Re: [Tiff] 16bit compressed colormaps", by Joris
2004.09.21 16:16 "Re: [Tiff] Alias Sketchbook Multi-Layer Tiff Files -- Specification", by Ian Ameline
2004.09.20 21:30 "[Tiff] Alias Sketchbook Multi-Layer Tiff Files -- Specification", by Ian Ameline
2004.09.21 16:01 "Re: [Tiff] Alias Sketchbook Multi-Layer Tiff Files -- Specification", by Joris
2004.09.27 19:14 "Re: [Tiff] Alias Sketchbook Multi-Layer Tiff Files -- Specification", by Ian Ameline
2004.09.27 19:34 "Re: [Tiff] Alias Sketchbook Multi-Layer Tiff Files -- Specification", by Joris
2004.09.24 13:02 "Re: [Tiff] Alias Sketchbook Multi-Layer Tiff Files -- Specification", by Joris
2004.09.24 12:36 "[Tiff] Possible (tiny) bug in LZW code", by Joris
2004.09.24 13:30 "Re: [Tiff] Possible (tiny) bug in LZW code", by Joris

2004.09.02 01:27 "Re: [Tiff] Stacked tiffs with colourmaps", by Joris

Is there any easier/ more efficient way to do this? - it would seem to make sense if only one colourmap was added that all the planes could refer to.

See also http://www.asmail.be/msg0054796490.html, because subject returned in other thread.

Once or twice every couple of years, the TIFF 7.0 subject comes up. That is a tradition of almost a decade old, and I'm quite sure it'll continue for at least as long still. On such occasions, I always add that I'd like to see memory management in TIFF 7.0, and reference counting. That would solve your problem too, you could have one color map, counted-referenced in all IFD's.

Unfortunately, TIFF 6.0 doesn't include that. There is no legal solution to your problem, I think.

*But* if you are very sure that your files will not escape into the wild, and will not get edited by TIFF page-joggling or other tools, you could nevertheless write the color map only once, and state the same color map offset in all IFD's. That is *not legal* in TIFF 6.0, but it takes some analysis to detect even, so normal readers would not have any problems with the file. Neither would transcoders. Only apps that, for instance, delete pages and try to reuse lost memory writing other data into it and such, would cause problems.

I repeat that this is *not legally TIFF 6.0*. I also have no clue how to do it with LibTiff, should you nevertheless want to.

Joris Van Damme
info@awaresystems.be
http://www.awaresystems.be

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