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From: Phil Harvey <phil@owl.phy.queensu.ca>
Date: Mon, 2 Apr 2007 08:12:19 -0400
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Subject: [Tiff] EXIF JPEG Thumbnail in TIFF
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Status:   

I have a question about thumbnail images in TIFF
files:

An exiftool user complains that his GDAL utilities
don't like the thumbnail image that I am adding with
my exiftool utility.  It complains that IFD1 is missing
the required ImageWidth/ImageLength fields.  (See
http://trac.osgeo.org/gdal/ticket/1483 for the bug
report.)  But the EXIF specification clearly states
that ImageWidth/ImageLength fields should not be
included in IFD1 for a JPEG thumbnail image.  (See
http://www.exif.org/Exif2-2.PDF page 57.)

So my questions:

1) Does libtiff support JPEG thumbnail images in TIFF
files as per the EXIF specification?

2a) If so, is there something that GDAL should be
doing to avoid getting these errors from libtiff?

2b) If not, am I reading the EXIF specification correctly,
and if so what library does GDAL need to use to read
these images?

TIA

- Phil Harvey

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