libpano13 patch for missing ExtraSamples TIFF metadata

[Kevin Mehall]

libpano13 writes TIFF files with an alpha channel, but without the required ExtraSamples TIFF metadata tag indicating that the 4th channel is alpha.

With the incorrect metadata, applications based on libtiff (e.g. tiffinfo) print a warning when opening a file created by PTUncrop:

TIFFReadDirectory: Warning, Sum of Photometric type-related color channels and ExtraSamples doesn't match SamplesPerPixel. Defining non-color channels as ExtraSamples..

Pillow 9.1.0 (Python library) fails to load these images, though this has been fixed.

I couldn't figure out where libpano13's authoritative source repository is, or how to submit a pull request or equivalent, so I've attached the patch against libpano13 v2.9.21 here.

[johnfi...@gmail.com]

On Friday, May 13, 2022 at 2:37:51 AM UTC-4 kevin....@gmail.com wrote:

I couldn't figure out where libpano13's authoritative source repository is, or how to submit a pull request or equivalent, so I've attached the patch against libpano13 v2.9.21 here.

The project is here:

https://sourceforge.net/projects/panotools/

Under the "mercurial" tab that page links to

https://sourceforge.net/p/panotools/libpano13/ci/default/tree/

That page lets you browse the code and it gives the command for cloning the repository:

hg clone http://hg.code.sf.net/p/panotools/libpano13 panotools-libpano13

I don't know how to submit a pull request.  But you asked in the right place and I expect the maintainers will either accept the patch you posted or give instructions.

If someone silently applies your patch (without replying here) the above links will let you see that.

I am one of two maintainers of a fork of libpano13.  I'll wait at least a few days for action in the official version and then examine your patch for inclusion in the fork.

[T. Modes]

Hi Kevin,

kevin.... schrieb am Freitag, 13. Mai 2022 um 08:37:51 UTC+2:

libpano13 writes TIFF files with an alpha channel, but without the required ExtraSamples TIFF metadata tag indicating that the 4th channel is alpha.

With the incorrect metadata, applications based on libtiff (e.g. tiffinfo) print a warning when opening a file created by PTUncrop:

TIFFReadDirectory: Warning, Sum of Photometric type-related color channels and ExtraSamples doesn't match SamplesPerPixel. Defining non-color channels as ExtraSamples..

Thanks for the patch. You are right with your diagnose. I committed the changes to the repository. John has already given the links.

Thomas