2007.07.03 18:37 "[Tiff] BigTIFF extension?", by Phil Harvey

2007.07.05 16:23 "[Tiff] Re: BigTIFF", by Gary McGath

On Thu, Jul 05, 2007 at 10:14:47AM -0400, Gary McGath wrote:

Stick with reality. What do programmers/users know about TIFF, what does it stand for? Any part of that actually changed?

Compatibility with all existing software.

Please, do not make general assumptions. BigTIFF is compatible with existing software. We have open source solution (CVS HEAD of libtiff library that anyone can get and use) and Joris has his proprietary solution. So there is even more than 1 choice.

The possibility of modifying and rebuilding software to make it compatible is not the same as compatibility in existing software. If you run any existing TIFF reader on any BigTIFF file, the reader will be unable to interpret it.

If you have no possibility to rebuild your software with updated libtiff it is a problem, but it is not a problem for _every_ user and it is not a problem of _all_ software.

It _is_ a problem with all existing software. A new version of an application that previously supported only GIF might now support PNG; that doesn't make PNG a new version of GIF.

Joris wrote:

> We've seen that argument before. I've replied before (amongst other replies) > that the same goes for tiling in TIFF, it was not compatible with all

> existing software either. So far, nobody contradicted my reply, so let's > stop returning to square one in this part of the discussion.

The cases aren't the same. An older TIFF reader will recognize such a file as intended to be TIFF, and will get stuck only when it encounters certain tags. It's always been recognized that newer TIFF versions will have new tags. An existing TIFF reader will not recognize any BigTIFF file as TIFF.

There was apparently a suggestion somewhere far back in the list that libtiff support for BigTIFF is what's important. I'm particularly bothered by this line of argumentation. An open software format must not be defined by any particular implementation, however widespread.

Gary McGath
Digital Library Software Engineer
Harvard University Library Office for Information Systems