Re: [Gimp-developer] TIFF Deflate compression method writes proprietary/deprecated tag to file

[Michael Henning <drawoc darkrefraction com>]

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 <federicotg gmail com> 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<32946>
>
> If I use imagemagick's mogrify to create the tiff
> mogrify -path /home/user/ -compress Zip -depth 8 -format tif fotografía7.tif
>
> I get
> tiffdump /home/user/fotografía7.tif | grep Compression
> Compression (259) SHORT (3) 1<8>
>
> 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