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Re: PQ HDR in PNG - draft review

From: Fredrik Hubinette <hubbe@google.com>
Date: Sat, 20 May 2017 22:56:04 -0700
Message-ID: <CAEVbG5o5wdyiyCBbZ38sB+MTC3F-VCSDEYdCWzqfL0LM9_5BLA@mail.gmail.com>
To: Lars Borg <borg@adobe.com>
Cc: Chris Lilley <chris@w3.org>, "public-colorweb@w3.org" <public-colorweb@w3.org>
Ah, my mistake.
What we have implemented is support for parametric curves, which I had
incorrectly assumed was ICC V2.
Anything that can't be described with parametric curves, we use a 3D-LUT
for, which is both less accurate and less efficient.

    /Hubbe

On Sat, May 20, 2017 at 7:26 PM, Lars Borg <borg@adobe.com> wrote:

> For chrome to do  color management efficiently, everything needs to be
> done on the GPU.
> Tables are generally much less efficient than doing using math on the GPU,
> and my impression
> is that ICC v4 relies much more heavily on tables than ICC v2.
>
>
> Yes, I see the point, but I don’t see there being more LUTs in V4 profiles
> than in V2, rather the opposite.
> With v4 we can use the parametric curves instead of the sampled 1D LUTs in
> V2.
> For example the standard sRGB profile  (colorimetric intent) can be
> created entirely without LUTs in V4, but requires LUTs in V2.
> Ditto display profiles.
>
> Lars
>
Received on Sunday, 21 May 2017 05:56:41 UTC

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