Re: [Gimp-developer] Color management (UI perspective for GIMP 2.8)

2010-02-13 Thread yahvuu
David Gowers wrote:
> * Color selector colors must be stored in a profile independent
> colorspace (LAB?[1]). This ensures that we can paint any color onto
> any image and get the right result. Otherwise, we'd have to know the
> profile that the color was specified in, in order to use the correct
> color on the image we're painting in now.. which makes color storage
> way too heavyweight.
[..]
> * We should be able to a) specify colors outside of the color profile gamut
>   and b) clip the current color to the limits of the current color
> profile when painting, previewing etc.
>   b) should probably be a toggle, then it could be quite helpful in
> quick soft-proofing

simpler:

Color selectors give an overview of available colors and
display a few selected colors, namely fg/bg color plus history.


The range of available colors changes with the current working color space,
and the color selectors should reflect that. E.g. the colors inside the
'triangle' should change according to current working space.

The selected colors however, should be transferable between images and
thus need to be stored in an absolute color space. Gamut warnings
indicate when they are outside the current working space.
(They may well be outside of display gamut as well..)


everything IMHO,
yahvuu

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Re: [Gimp-developer] Color management (UI perspective for GIMP 2.8)

2010-02-12 Thread David Gowers
On Sat, Feb 13, 2010 at 8:59 AM, SHIRAKAWA Akira
 wrote:
> On 2010-02-09 19:52, Martin Nordholts wrote:
>> "GIMP is nearly flawless in its color handling, but there is one
>> problem. It forgets to convert copy and pasted image content."
>
> Also don't forget that the various color picker/selectors aren't color
> managed at the moment, so selected colors (FG/BG colors) will look
> differently when painted on a color managed image.

I think color management of individual colors and color selectors is a
tricky subject.

* Color selector colors must be stored in a profile independent
colorspace (LAB?[1]). This ensures that we can paint any color onto
any image and get the right result. Otherwise, we'd have to know the
profile that the color was specified in, in order to use the correct
color on the image we're painting in now.. which makes color storage
way too heavyweight.

* We should consider improving the color history system.
  MyPaint has one with the property that I think is important here: A
color gets added to the history once it is 'read' (in Mypaint's case,
when you paint with it;
   In GIMP's case, this would also be if it was read via the PDB (ie
plugins or scripts)). And the previous color is shown in the color
selector side-by-side to
the color you're now adjusting. This makes it easier to do color
comparisons, which are pretty important to get right when the previous
color and current color are based on different color profiles.

* We should be able to a) specify colors outside of the color profile gamut
  and b) clip the current color to the limits of the current color
profile when painting, previewing etc.
  b) should probably be a toggle, then it could be quite helpful in
quick soft-proofing

* Some of the color selectors are already quite slow (eg. the 'scales' one).
  We should avoid making them slower if possible.

[1] correct me if I'm wrong here... scRGB might do the job okay, I'm
not 100% sure.
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Re: [Gimp-developer] Color management (UI perspective for GIMP 2.8)

2010-02-12 Thread SHIRAKAWA Akira
On 2010-02-09 19:52, Martin Nordholts wrote:
> "GIMP is nearly flawless in its color handling, but there is one
> problem. It forgets to convert copy and pasted image content."

Also don't forget that the various color picker/selectors aren't color 
managed at the moment, so selected colors (FG/BG colors) will look 
differently when painted on a color managed image.

-- 
SHIRAKAWA Akira
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Re: [Gimp-developer] Color management (UI perspective for GIMP 2.8)

2010-02-09 Thread Martin Nordholts
On 02/08/2010 07:07 PM, yahvuu wrote:
> From the User Scenarios [1], i'd like to pick "Creating Original Art",
> short name: "create a collage". This seems to be the clearest case,
> and perhaps the others can be modelled after this one.
>
> Compositing several images into one image requires that all parts
> have the same color space. The work is saved as XCF.
>
> Interestingly, from this follows that the working color space is not
> a preference item, but a property of the image (XCF). Instead,
> the _default_ image's color space is a preference item. The color
> space should be set by choosing a template or from the Image->Mode menu.
>
>
> For collage work, 'open as layers' can safely auto-convert to working color 
> space:
> if a to-be-imported image requires manual color space adjustment,
> it can be opened as an image on its own, be converted and then just be
> dragged to the collage. So dragging layers between images should
> silently auto-convert, too.

This problem was observed in the excellent GIMP 2.6 review by Ars Technica:

"GIMP is nearly flawless in its color handling, but there is one 
problem. It forgets to convert copy and pasted image content."

http://arstechnica.com/features/2009/01/gimp-2-6-review.ars/2

> Somewhat related, why is 'color management' available as a display filter?
> The name suggests it's a filter between image and monitor, so at most
> the monitor profile(s) may be chosen here.

As far as I know this is just an implementation detail leaking out in 
the UI: color managaing the viewing of an image is handled internally 
through a display filter.

Regards,
Martin
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