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April 2004

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2004.04.15 00:26 "Large TIFF files", by Lynn Quam
2004.04.15 01:57 "Re: Large TIFF files", by Frank Warmerdam
2004.04.15 02:17 "Re: Large TIFF files", by Lynn Quam
2004.04.15 04:41 "Re: Large TIFF files", by Chris Cox
2004.04.15 06:05 "Re: Large TIFF files", by Rob Tillaart
2004.04.15 12:23 "Re: Large TIFF files", by Dan Smith
2004.04.15 13:33 "Re: Large TIFF files", by Frank Warmerdam
2004.04.15 21:51 "Re: Large TIFF files", by Chris Cox
2004.04.16 17:23 "Re: Large TIFF files", by Joris Van Damme
2004.04.17 02:50 "Re: Large TIFF files", by Joris Van Damme
2004.04.20 08:29 "Re: Large TIFF files", by Rob Tillaart
2004.04.20 14:20 "Re: Large TIFF files", by Joris Van Damme
2004.04.21 07:06 "Re: Large TIFF files", by Rob Tillaart
2004.04.20 20:44 "Re: Large TIFF files", by Chris Cox
2004.04.21 07:30 "Re: Large TIFF files", by Rob Tillaart
2004.04.21 17:54 "Re: Large TIFF files", by Chris Cox
2004.04.22 07:38 "Re: Large TIFF files", by Rob Tillaart
2004.04.22 18:21 "Re: Large TIFF files", by Chris Cox
2004.04.22 18:34 "Re: Large TIFF files", by Thomas J Kacvinsky
2004.04.22 18:43 "Re: Large TIFF files", by Chris Cox
2004.04.22 18:49 "Re: Large TIFF files", by Bob Friesenhahn
2004.04.22 19:52 "Re: Large TIFF files", by Phillip Crews
2004.04.22 20:45 "Re: Large TIFF files", by Andrey Kiselev
2004.04.22 21:06 "Re: Large TIFF files", by Chris Cox
2004.04.22 21:35 "Re: Large TIFF files", by Joris Van Damme
2004.04.22 21:49 "Re: Large TIFF files", by Bob Friesenhahn
2004.04.22 21:59 "Re: Large TIFF files", by Chris Cox
2004.04.22 22:23 "Re: Large TIFF files", by Bob Friesenhahn
2004.04.22 22:31 "Re: Large TIFF files", by Joris Van Damme
2004.04.22 22:34 "Re: Large TIFF files", by Chris Cox
2004.04.22 23:03 "Re: Large TIFF files", by Joris Van Damme
2004.04.22 23:17 "Re: Large TIFF files", by Bob Friesenhahn
2004.04.22 23:59 "Re: Large TIFF files", by Chris Cox
2004.04.23 15:58 "Re: Large TIFF files", by Leonard Rosenthol
2004.04.26 14:50 "Re: Large TIFF files", by Marco Schmidt
2004.04.23 12:45 "Re: Large TIFF files", by John Aldridge
2004.04.23 13:12 "Re: Large TIFF files", by Joris Van Damme
2004.04.23 20:37 "Re: Large TIFF files", by Bob Friesenhahn
2004.04.23 22:31 "Re: Large TIFF files", by Chris Cox
2004.04.23 22:38 "Re: Large TIFF files", by Bob Friesenhahn
2004.04.23 22:58 "Re: Large TIFF files", by Chris Cox
2004.04.26 10:03 "Re: Large TIFF files", by Joris Van Damme
2004.04.26 14:32 "Re: Large TIFF files", by Bob Friesenhahn
2004.04.26 07:30 "Re: Large TIFF files", by Rob Tillaart
2004.04.26 09:58 "Re: Large TIFF files", by Joris Van Damme
2004.04.26 11:06 "Re: Large TIFF files", by Rob Tillaart
2004.04.26 11:28 "Re: Large TIFF files", by Joris Van Damme
2004.04.26 12:05 "Re: Large TIFF files", by John Aldridge
2004.04.26 12:33 "Re: Large TIFF files", by Joris Van Damme
2004.04.26 12:53 "Re: Large TIFF files: explicitly different format", by Dan Smith
2004.04.26 13:16 "Re: Large TIFF files: explicitly different format", by Joris Van Damme
2004.04.26 17:10 "Re: Large TIFF files: explicitly different format", by Chris Cox
2004.04.26 11:38 "Re: Large TIFF files", by Gerben Vos
2004.04.26 12:50 "Re: Large TIFF files", by Joris Van Damme
2004.04.27 06:12 "Re: Large TIFF files", by Rob Tillaart
2004.04.26 16:54 "Re: Large TIFF files", by Chris Cox
2004.04.23 13:16 "Re: Large TIFF files", by Phillip Crews
2004.04.23 20:28 "Re: Large TIFF files", by Andrey Kiselev
2004.04.23 15:54 "Re: Large TIFF files", by Leonard Rosenthol
2004.04.22 10:32 "Re: Large TIFF files", by Gerben Vos
2004.04.22 18:41 "Re: Large TIFF files", by Chris Cox
2004.04.22 19:45 "Re: Large TIFF files", by Dan Smith
2004.04.22 20:08 "Re: Large TIFF files", by Chris Cox

2004.04.15 13:33 "Re: Large TIFF files", by Frank Warmerdam

Rob van den Tillaart wrote:
> Hi,
> 
> Are there people currently active to define a "64 bit tiff" proposal?
> Is there a list of proposed alternatives?

Rob,

I don't think there is anyone actively working on this.  However, I propose
that we re-initiate a discussion on this topic here on the list.  This has
been percolating in the back of my mind for several years.  My current thinking
is that we should:

  o Introduce a new data type TIFF_LONGLONG = 14 which is a 64 bit integer value.
  o Allow as a non-core extention the option of having the strip offsets or
    tile offsets as TIFF_LONGLONG.
  o leave everything else the same.

This approach has a number of downsides compared to a complete 64-bit conversion.
Primarily that only image tiles and strips can be managed beyond the 4GB barrier.
This makes places the onus on applications wanting to write large files to
ensure that all other data items (the directory, and all references data
objects like color table, description and so forth) are written out in the
first 4GB of the file.

On the plus side, it would be a relatively modest effort to modify existing
TIFF libraries to support such an approach - for reading at least.

Another approach of course would be to alter all offsets to be 64 bit which
would be much more general, but require more substantial changes to supporting
libraries.  It would also pretty much require a new magic code and we would not
really be within our rights to call the result TIFF.

Which ever approach is taken, I would intend to produce a libtiff that supported
both the new "big" format and the existing 32bit format.  Ideally, libtiff
would produce old style files normally, and switch over to producing the big
format for large images.

The other issue that arises is whether we should actively try to get Adobe to
lead a new TIFF specification or just produce something ourselves as a community.
While it would be nice to have Adobe's involvement, I am not keen on waiting
for them.

One thing I would really like is some indication of what other TIFF
implementations exist out there beyond libtiff, and if their developers would
be interested in working cooperatively on a 64 bit TIFF standard.  I know that
folks like LEADtools must have their own.  Adobe likely does.  In the remote
sensing field I know most vendors use libtiff (or hacked variations thereof)
but I think some folks (Intergraph?) have their own TIFF libraries.  It would
be nice to get some non-libtiff folks involved in a 64 bit TIFF specification
effort.  Perhaps especially the folks who produce the scanners that need to
produce big files.

By the way, I would forsee a 64 bit TIFF specification (which I imagine
we would have to call something different - perhaps BTIFF - Big Tagged
Image File Format) being developed essentially only defining low level
structural details, with all higher level concepts (tag lists, values and
so on) defined by reference to the TIFF 6 specification.

Best regards,
-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam@pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent