HDR support in Wayland/Weston

Chris Murphy lists at colorremedies.com
Thu Jan 31 19:03:25 UTC 2019

Hi Ankit,

On Wed, Jan 30, 2019 at 10:54 PM Nautiyal, Ankit K
<ankit.k.nautiyal at intel.com> wrote:
> Hi Ole,
> I was going through the protocol you had proposed, and have some silly
> questions, please pardon my ignorance.
>  From where can the client-applications get the ICC profile files? Does
> the client application manufacture it for a given color space and a
> standard template?

I'm pretty sure most every desktop environment and distribution have
settled on colord as the general purpose service.

By default, colord will create a display profile on-the-fly, for
attached displays, based on display provided EDID information. There
can be buggy EDID, and in practice there are no display updates to fix
it after the product ships. Whether this is sanity checked prior to
building a profile, or later, depends on the policy of the platform at
the time the buggy EDID is encountered. Where it's sanity checked also
varies: it could be the platform specific profile manager e.g. colord;
the color management module (CMM) which is the engine that uses
profiles to perform color space transforms; or it could happen at the
application level.

Profiles are sometimes packaged with applications, sometimes stand
alone. Argyll CMS includes a bunch of standardized RGB profiles,
Ghostscript includes another set, and colord includes some as well.

You're definitely best off deferring to tools that specialize in
creating ICC profiles rather than building them yourself.

> Or the compositor needs to store .icc files for each of the
> color-spaces, which the clients can use.
> Also, are there already libraries that can be user to parse the .icc files?
> I can see some recommended by ICC, like SampleICC, Argyll etc, is there
> something which suits our case better?

You'd want to evaluate the interfaces of Argyll CMS and lcms2; it's
possible you'd use Argyll CMS for profile creation, and lcms2 as the
transformation engine, for example.


Chris Murphy

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