[Qgis-user] TIFF tag 33723 IPTC metadata

[Greg Coats]

When Photoshop writes a .tif file, it automatically includes TIFF tag  
700 XMP metadata, and TIFF tag 33723 IPTC metadata. The TIFF utilities  
tiffcp and geotifcp copy these Photoshop created .tif files. For  
example, the commands below read in image1.tif, and then write  
image2.tif, arranged into tiles 256x256, and include the XMP and IPTC  
metadata.
$ tiffcp   -t -w 256 -l 256 image1.tif image2.tif
$ geotifcp -t -w 256 -l 256 image1.tif image2.tif

The (unofficial ?) web page
http://www.awaresystems.be/imaging/tiff/tifftags/iptc.html
identifies TIFF tag 33723 IPTC as Type=UNDEFINED or 7, and yet  
tiffinfo shows that the Photoshop created .tif files have TIFF tag  
33723 IPTC written as Type=LONG or 4. Why this difference?

The Kakadu version 6.3.0 supports reading and writing TIFF tag 700 XMP  
metadata, and TIFF tag 33723 IPTC metadata. There is no problem with  
XMP metadata, but when writing IPTC metadata, kdu_expand writes TIFF  
tag 33723 IPTC as Type=UNDEFINED or 7, in compliance with the  
awaresystems web page.

But then I observe that tiffcp and geotifcp both report the Kakadu  
written .tif has an "Incompatible type" for its TIFF tag 33723 IPTC  
metadata, even though the type conforms to the awaresystems web page,  
although that is different from what Adobe uses in Photoshop, and as a  
result the IPTC metadata is lost, and not included in the output .tif  
file.

$ geotifcp -t -w 256 -l 256 image01_v6_3_x86_03_64.tif  
image01_v6_3_x86_03_64_kduV630_1.tif
TIFFFetchNormalTag: Warning, Incompatible type for "RichTIFFIPTC"; tag  
ignored.

Should I change the Kakadu source code so that it makes the same  
mistake Photoshop makes, and identifies TIFF tag 33723 IPTC metadata  
as Type=LONG or 4?
Greg
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