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September 2004

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2004.09.16 19:12 "BigTIFF Tag Value Count issue", by Joris Van Damme
2004.09.16 19:23 "Re: BigTIFF Tag Value Count issue", by Frank Warmerdam
2004.09.16 19:36 "Re: BigTIFF Tag Value Count issue", by Joris Van Damme
2004.09.16 19:38 "Re: BigTIFF Tag Value Count issue", by Frank Warmerdam
2004.09.16 20:08 "Re: BigTIFF Tag Value Count issue", by Joris Van Damme
2004.09.17 01:14 "Re: BigTIFF Tag Value Count issue", by Bob Friesenhahn
2004.09.16 22:39 "Re: BigTIFF Tag Value Count issue", by Ian Ameline
2004.09.17 00:09 "Re: BigTIFF Tag Value Count issue", by Bob Friesenhahn
2004.09.17 00:32 "Re: BigTIFF Tag Value Count issue", by Joris Van Damme
2004.09.17 01:54 "Re: BigTIFF Tag Value Count issue", by Bob Friesenhahn
2004.09.17 02:29 "Re: BigTIFF Tag Value Count issue", by Bob Friesenhahn
2004.09.17 02:58 "Re: BigTIFF Tag Value Count issue", by Bob Friesenhahn
2004.09.17 03:08 "Re: BigTIFF Tag Value Count issue", by Chris Cox
2004.09.17 04:20 "Re: BigTIFF Tag Value Count issue", by Bob Friesenhahn
2004.09.17 04:39 "Re: BigTIFF Tag Value Count issue", by Chris Cox
2004.09.17 11:25 "Re: BigTIFF Tag Value Count issue", by Joris Van Damme
2004.09.17 14:31 "Re: BigTIFF Tag Value Count issue", by Bob Friesenhahn
2004.09.17 14:40 "Re: BigTIFF Tag Value Count issue", by Frank Warmerdam
2004.09.17 15:02 "Re: BigTIFF Tag Value Count issue", by Bob Friesenhahn
2004.09.17 21:41 "Re: BigTIFF Tag Value Count issue", by Chris Cox
2004.09.17 14:53 "Re: BigTIFF Tag Value Count issue", by Joris Van Damme
2004.09.17 15:06 "Re: BigTIFF Tag Value Count issue", by Bob Friesenhahn
2004.09.17 21:36 "Re: BigTIFF Tag Value Count issue", by Chris Cox
2004.09.17 05:46 "Re: BigTIFF Tag Value Count issue", by Frank Warmerdam
2004.09.17 11:40 "Re: BigTIFF Tag Value Count issue", by Joris Van Damme
2004.09.17 13:11 "Re: BigTIFF Tag Value Count issue", by Frank Warmerdam
2004.09.17 13:34 "Re: BigTIFF Tag Value Count issue", by Joris Van Damme
2004.09.17 15:10 "Re: BigTIFF Tag Value Count issue", by Fernando Loygorri
2004.09.17 15:10 "Re: BigTIFF Tag Value Count issue", by Bob Friesenhahn
2004.09.17 15:55 "Re: BigTIFF Tag Value Count issue", by Fernando Loygorri
2004.09.17 16:00 "Re: BigTIFF Tag Value Count issue", by Frank Warmerdam
2004.09.17 16:33 "Re: BigTIFF Tag Value Count issue", by Fernando Loygorri
2004.09.17 16:13 "Re: BigTIFF Tag Value Count issue", by Joris Van Damme
2004.09.17 16:34 "Re: BigTIFF Tag Value Count issue", by Fernando Loygorri
2004.09.17 16:43 "Re: BigTIFF Tag Value Count issue", by Bob Friesenhahn
2004.09.17 21:48 "Re: BigTIFF Tag Value Count issue", by Ross A Finlayson
2004.09.17 22:15 "Re: BigTIFF Tag Value Count issue", by Bob Friesenhahn
2004.09.17 21:41 "Re: BigTIFF Tag Value Count issue", by Chris Cox
2004.09.17 11:38 "Re: BigTIFF Tag Value Count issue", by Joris Van Damme
2004.09.17 06:35 "Re: BigTIFF Tag Value Count issue", by Rob Tillaart
2004.09.17 11:43 "Re: BigTIFF Tag Value Count issue", by Joris Van Damme
2004.09.17 12:46 "Re: BigTIFF Tag Value Count issue", by Rob Tillaart
2004.09.17 12:55 "Re: BigTIFF Tag Value Count issue", by Joris Van Damme
2004.09.17 13:20 "Re: BigTIFF Tag Value Count issue", by Rob Tillaart
2004.09.17 13:47 "Re: BigTIFF Tag Value Count issue", by Joris Van Damme
2004.09.17 13:08 "Re: BigTIFF Tag Value Count issue", by Ross A Finlayson
2004.09.19 12:31 "Re: BigTIFF Tag Value Count issue", by Andrey Kiselev
2004.09.19 16:43 "Re: BigTIFF Tag Value Count issue", by Joris Van Damme
2004.09.20 16:18 "Re: BigTIFF Tag Value Count issue", by Ed Grissom
2004.09.20 22:05 "Re: BigTIFF Tag Value Count issue", by Steve Carlsen
2004.09.20 23:09 "Re: BigTIFF Tag Value Count issue", by Bob Friesenhahn

2004.09.17 04:39 "Re: BigTIFF Tag Value Count issue", by Chris Cox

> > > > Option 0: stick with 4 byte tag count members (alignment, tag 
> > > > data <= 4 gig, Frank's choice)
> > > > Option 1: make it an 8 byte tag count (no alignment, tag data > 4 
> > > > gig allowed)
> > > > Option 2, courtesy of Bob: make it 8 byte tag count, add 4 padding bytes
> > > > (alignment, tag data > 4 gig allowed)
> > > >
> > > > Can I put you down as an option 2 vote, or were you merely signalling the
> > > > option?
> > >
> > > Sure, there should always be a second option so put me down for 
> > > option 2. :-)
> >
> > Can you think of a situation that needs an 8 byte count?
> > Or do you just want the size increased on general principles?
>
> The idea was to consume 8 bytes for alignment purposes but use 4 
> bytes out of those 8 bytes to support the value.  Perhaps I 
> misunderstood the problem.  I don't have a strong opinion either 
> way, but do believe that the format should be aligned to work well 
> with memory-mapping.

I'm not sure we can guarantee 8 byte alignment of the IFD, so how can 
we guarantee that the items will be aligned in memory?


> > Do you think that increasing the count to 8 bytes would be a 
> > problem in libTIFF?
>
> I don't have the libtiff knowledge to properly answer that.  If the 
> availability of a native 64-bit storage type can be assumed (pretty 
> safe if 32-bit processors are the new baseline) then it doesn't 
> sound like an 8 byte value would be a problem.

I was thinking more of logic changes necessary.
In Photoshop the count field is well isolated - it would take about 
80 lines of code to change the count from 4 to 8 bytes. (mostly range 
checking and increasing the size of loop variables)

Chris