[gdal-dev] Updating value for Compression tag for JPEGXL in TIFF to the one of DNG 1.7 ?

[Kurt Schwehr]

Sounds good to me too (not that I really have the background to say so).

1. Are there any plans to contribute JPEGXL in tiff to
https://gitlab.com/libtiff/libtiff?
2. And what would one need to do to patch libtiff to use JPEGXL?

Thanks!

On Mon, Jan 6, 2025 at 9:54 AM thomas bonfort via gdal-dev <
gdal-dev at lists.osgeo.org> wrote:

> sounds good, +1
>
> thanks,
> TB
>
> Le lun. 6 janv. 2025, 18:44, Even Rouault via gdal-dev <
> gdal-dev at lists.osgeo.org> a écrit :
>
>> Hi,
>>
>> Given that communication with Adobe in recent years has been similar to
>> expecting to receive a signal from a black hole from outside its event
>> horizon, up to now we have unilaterally attributed Compression=50002 to
>> mean JPEGXL in TIFF. Recently I saw that the DNG 1.7 specification has
>> registered value 52546 to mean JPEGXL in DNG
>> (
>> https://helpx.adobe.com/content/dam/help/en/photoshop/pdf/DNG_Spec_1_7_0_0.pdf
>> , page 122). DNG is a derivative of the TIFF spec, so I guess/hope Adobe
>> makes sure that tag & tag value numbers don't collide between base TIFF
>> and DNG. So it would seem to me that switching to using the 52546 value
>> would be more future proof than our self-assigned 50002. If so, I'd do
>> the change in master to using 52546 on write side and accepting both
>> 50002 and 52546 on read side, and backport read support for 52546 in 3.10
>>
>> (this is mostly a GDAL-only topic for now given that the JPEGXL TIFF
>> codec is for the internal libtiff copy only)
>>
>> Thoughts?
>>
>> Even
>>
>> --
>> http://www.spatialys.com
>> My software is free, but my time generally not.
>> Butcher of all kinds of standards, open or closed formats. At the end,
>> this is just about bytes.
>>
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