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From: "Joris Van Damme \(AWare Systems\)" <joris.at.lebbeke@skynet.be>
To: "Grissom, Ed" <ed.grissom@intergraph.com>,
        "libTIFF List" <tiff@lists.maptools.org>
References: <AA6DDFA4E046A24585BC828A78155B47037D013C@US-MAIL.ingrnet.com>
Subject: Re: [Tiff] BigTIFF documentation
Date: Thu, 17 Apr 2008 08:09:15 +0200
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Status:   

Ed,

Grissom, Ed wrote:
> I notice that Joris' page (1), and the sample BigTIFFs both use a
> 8-byte 'count' or 'number of values' field in each tag.
>
> But that fact is not mentioned on the "Design" page (2) as being a
> change from the classic TIFF spec to the new BigTIFF spec.
>
> (1) http://www.awaresystems.be/imaging/tiff/bigtiff.html
>
> (2) http://www.remotesensing.org/libtiff/bigtiffdesign.html

The 8byte tag count has been the subject of a lengthy discussion on the 
list. And I mean lengthy (see http://www.asmail.be/msg0054796491.html).

If I remember correctly, there was no official discussion to that debate, 
but the people that went ahead adopted the 8byte option. I'm resisting the 
temptation to state our reasons, as I don't want to redo that same 
discussion over again. In any case, there's two independent BigTIFF 
implementations both using the 8byte count size, and to my knowledge no 
other.

I believe at the time the 'Design' wiki was dead already. A security issue 
in the wiki code, if I remember correctly. Thus, that page wasn't updated. 
What you're pointing to is a non-wiki copy of that page that was created 
later on, just to preserve and publish what used to be in the wiki, but 
without any intention to keep it up to date.


Best regards,

Joris Van Damme
info@awaresystems.be
http://www.awaresystems.be/
Download your free TIFF tag viewer for windows here:
http://www.awaresystems.be/imaging/tiff/astifftagviewer.html

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