Re: [Gimp-developer] sRGB was second worst performer against spectral reference

2015-05-13 Thread Gez
El mié, 13-05-2015 a las 10:36 +0200, Simon Budig escribió:
> Simone Karin Lehmann (sim...@lisanet.de) wrote:
> > No, the conclusion is quiet easy. And it’s what Elle says for, AFAIK,
> > more than a year.
> 
> ...and what the GIMP developers have accepted for more than a year.
> 
> Just for the records.

(not arguing or trying to bring back the neverending thread, just asking
"for the records")

What's the immediate plan for 2.10? It's still using unbounded sRGB for
the working RGB pixel formats?
As it was already discussed, that would be enough for keeping things
more or less consistent with earlier versions of GIMP (i.e. getting sRGB
right) and fast, but potentially problematic when dealing chromaticity
dependent operations and wider gamut colorspaces.

I've been told that the goal is to release 2.10 with GEGL providing the
same functionalities and keeping the legacy appearance of legacy files
as soon as possible and then take care of specific color management in
future versions.
That seems a reasonable plan, of course, but I'm curious about how the
program will deal with non-sRGB images if editing them in the source
colorspace won't be possible and some operations are likely to fail with
unbounded sRGB.
Forcing a bounded conversion to sRGB for the time being could be a
solution, although quite unpopular for anyone using anything but sRGB.
 
Or is there still chances of an "anyRGB" pixelformat allowing working on
the artist's colorspace of choice for 2.10?

Gez.

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Re: [Gimp-developer] sRGB was second worst performer against spectral reference

2015-05-13 Thread Simon Budig
Simone Karin Lehmann (sim...@lisanet.de) wrote:
> No, the conclusion is quiet easy. And it’s what Elle says for, AFAIK,
> more than a year.

...and what the GIMP developers have accepted for more than a year.

Just for the records.

Bye,
   Simon

-- 
  si...@budig.de  http://simon.budig.de/
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Re: [Gimp-developer] sRGB was second worst performer against spectral reference

2015-05-13 Thread Simone Karin Lehmann

> Am 13.05.2015 um 07:52 schrieb Nicolas Robidoux :
> 
> "We won't provide any conclusions because the results in the given tests
> context are self explanatory."
> 
> This is another way to say: "Trying to put things in context so that the
> results are relevant to real life would expose us to criticism, so we'll
> say it's obvious so that other people get the dunce cap."


No, the conclusion is quiet easy. And it’s what Elle says for, AFAIK, more than 
a year.

Results of operations on RGB data depend on the given RGB primaries and will 
differ with different RGB primaries. So, all operations on user RGB data should 
only use user RGB primaries and not sRGB primaries or any other RGB primaries 
chosen by developers.

Simone Karin
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Re: [Gimp-developer] sRGB was second worst performer against spectral reference

2015-05-12 Thread Nicolas Robidoux
"We won't provide any conclusions because the results in the given tests
context are self explanatory."

This is another way to say: "Trying to put things in context so that the
results are relevant to real life would expose us to criticism, so we'll
say it's obvious so that other people get the dunce cap."

On 12 May 2015 at 23:21, Elle Stone  wrote:

> As the GIMP 2.10 release edges closer, I thought GIMP devs and GIMP users
> might want to look at the following article:
>
> http://colour-science.org/blog_about_rgb_colourspace_models_performance.php
>
> Of 29 compared RGB working spaces, sRGB came in second-worst in a
> comparison of performance against spectral reference. AdobeRGB1998 ranked
> 15th from the top, ProPhotoRGB 17th from the top.
>
> BetaRGB came in at the very top. Of the larger gamut color spaces,
> Rec.2020 and two ACES variants were in the top ten.
>
> Quoting the introduction to the article:
>
> "The purpose of this document is to compare RGB colourspace models
> operations performance against spectral reference."
>
> "Various mathematical operations because of the nature of matrices and
> linear algebra are dependent on given RGB colourspace primaries. The same
> operations performed in different RGB colourspaces will yield different
> tristimulus values once converted back to CIE XYZ colourspace. For example
> multiplication, division and power operations are RGB colourspace primaries
> dependent while addition and subtraction are not."
>
> Quoting the conclusion: "We won't provide any conclusions because the
> results in the given tests context are self explanatory."
>
> The study suggests that sRGB is just about the worst possible color space
> you could use for image editing.
>
> Best regards,
> Elle Stone
> --
> http://ninedegreesbelow.com
> Color management and free/libre photography
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[Gimp-developer] sRGB was second worst performer against spectral reference

2015-05-12 Thread Elle Stone
As the GIMP 2.10 release edges closer, I thought GIMP devs and GIMP 
users might want to look at the following article:


http://colour-science.org/blog_about_rgb_colourspace_models_performance.php

Of 29 compared RGB working spaces, sRGB came in second-worst in a 
comparison of performance against spectral reference. AdobeRGB1998 
ranked 15th from the top, ProPhotoRGB 17th from the top.


BetaRGB came in at the very top. Of the larger gamut color spaces, 
Rec.2020 and two ACES variants were in the top ten.


Quoting the introduction to the article:

"The purpose of this document is to compare RGB colourspace models 
operations performance against spectral reference."


"Various mathematical operations because of the nature of matrices and 
linear algebra are dependent on given RGB colourspace primaries. The 
same operations performed in different RGB colourspaces will yield 
different tristimulus values once converted back to CIE XYZ colourspace. 
For example multiplication, division and power operations are RGB 
colourspace primaries dependent while addition and subtraction are not."


Quoting the conclusion: "We won't provide any conclusions because the 
results in the given tests context are self explanatory."


The study suggests that sRGB is just about the worst possible color 
space you could use for image editing.


Best regards,
Elle Stone
--
http://ninedegreesbelow.com
Color management and free/libre photography
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