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April 2005

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2005.04.29 22:52 "Color TIFF/JPEG compression questions", by Jason Frank
2005.04.29 23:16 "Re: Color TIFF/JPEG compression questions", by Joris Van Damme
2005.04.30 15:51 "Re: Color TIFF/JPEG compression questions", by Jason Frank
2005.04.30 07:08 "Re: Color TIFF/JPEG compression questions", by Andrey Kiselev
2005.05.02 13:44 "Re: Color TIFF/JPEG compression questions", by Ed Grissom
2005.05.02 14:16 "Re: Color TIFF/JPEG compression questions", by Joris Van Damme
2005.05.02 16:12 "Re: Color TIFF/JPEG compression questions", by Jason Frank
2005.05.02 16:29 "Re: Color TIFF/JPEG compression questions", by Jason Frank
2005.05.02 17:55 "Re: Color TIFF/JPEG compression questions", by Joris Van Damme
2005.05.02 18:17 "Re: Color TIFF/JPEG compression questions", by Jason Frank
2005.05.02 18:43 "Re: Color TIFF/JPEG compression questions", by Joris Van Damme
2005.05.02 18:48 "Re: Color TIFF/JPEG compression questions", by Bob Friesenhahn
2005.05.02 18:48 "Re: Color TIFF/JPEG compression questions", by Jason Frank
2005.05.02 19:11 "Re: Color TIFF/JPEG compression questions", by Andrey Kiselev
2005.05.03 05:46 "Re: Color TIFF/JPEG compression questions", by Andrey Kiselev

2005.05.02 18:43 "Re: Color TIFF/JPEG compression questions", by Joris Van Damme

Jason

> So, I think that tiffinfo might be playing correctly here (since it
> agrees with tiffdump, and I don't see any obvious problems with the
> code.)

We should check that we are talking about the exact same quad-jpeg.tif. I know
for a fact that AsTiffTagViewer shows exactly what is there, and, unlike
LibTiff, that stuff isn't burdoned with an actual image decoder part and a
subsampling-fixup scheme and such... So if AsTiffTagViewer doesn't mention the
tag, and tiffinfo does, I know for a fact that tiffinfo must be wrong.

A newer version of AsTiffTagViewer that isn't published yet, also supports hex
viewing of just about any structure in a TIFF file. With this version I was able
to triple-check, and sure enough, the tag count of this IFD shows as 14 in a hex
dump that is merely a hex dump and cannot possibly be wrong. 14 is the number of
tags shown by both versions of AsTiffTagViewer. So tiffinfo *does* add the
default or fixed-up or whatever values of YCbCrSubsampling even though the tag
is *not* there.

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