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April 2007
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2007.04.02 12:12 "EXIF JPEG Thumbnail in TIFF", by Phil Harvey
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