2012.11.24 00:09 "[Tiff] help writing thumbnails to TIFF file?", by Paul
Heckbert
Thread
2012.12.13 14:50 "Re: [Tiff] IFD offset tags written with wrong DataType in libtiff 4.0.3", by Bob Friesenhahn
On Wed, 12 Dec 2012, Paul Heckbert wrote:
I have a test program that uses libtiff to create an EXIF IFD, and I found that with libtiff version 4.0.3, the TIFFTAG_EXIFIFD tag was being written with TIFFDataType TIFF_IFD into Classic TIFF files (TIFF files that are not BigTIFF). Unfortunately, TIFF_IFD=13 is a new type and is not yet standard. Much existing software expects the EXIFIFD tag to have type TIFF_LONG=4 and will not read the EXIF tags if the type is written as TIFF_IFD. This means that writing of EXIF tags is not working as broadly as possible with libtiff version 4.0.3.
This is all very interesting. If TIFF_LONG is used, what should we do while writing BigTIFF format? Should TIFF_LONG only be used for Classic TIFF?
Bob
--
Bob Friesenhahn
bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/