Fixed in master and 2.8. Thank you for reporting this.

commit cd4d5e6d32169e0d642010b992ad401244db354d Author: Michael Henning
Date: Fri Sep 20 19:05:18 2013 -0400

plug-ins: Use the standardized value for deflate compression in tiff-save.

Ironically, the standardized value is called COMPRESSION_ADOBE_DEFLATE, while the vendor-specific value is called COMPRESSION_DEFLATE.

On Fri, Sep 20, 2013 at 12:10 PM, Federico wrote:

Hi.
I noticed GIMP 2.8.4 is writing the proprietary ZIP/Flate compression code (0x80b2) when exporting images in TIFF format and selecting deflate compression.
According to the TIFF Revision 6.0, Supplement 2 ( http://partners.adobe.com/public/developer/en/tiff/TIFFphotoshop.pdf) the value for the Compression tag should be 0008.

I can confirm Gimp is writing the proprietary tag by exporting a deflated tiff and running

tiffdump 1.tif | grep Compression Compression (259) SHORT (3) 1

If I use imagemagick's mogrify to create the tiff mogrify -path /home/user/ -compress Zip -depth 8 -format tif fotografa7.tif

I get tiffdump /home/user/fotografa7.tif | grep Compression Compression (259) SHORT (3) 1

The compression algorithm is the same, only the code is changed for a standard value. As TIFF is used for long term archiving, the generating the files with the standard value is important for future implementations that may not understand the proprietary tag.

Should I file a bug? Do you think it is important?

Here's a section of the spec:

"Note: A proprietary ZIP/Flate compression code (0x80b2) has been used by some software vendors. This code
should be considered obsolete. The compression used by the obsolete code is identical to that defined
above. We recommend that TIFF implementations recognize and read the obsolete code, but only write the
official compression code (8)."
_______________________________________________ gimp-developer-list mailing list
List address: gimp-developer-list@gnome.org List membership: https://mail.gnome.org/mailman/listinfo/gimp-developer-list