On 02/07/2010 04:55 AM, Omari Stephens wrote:
> Hi, all
> I wrote up a quick spec for how GIMP should deal with color profiles
> associated with files and images. The spec is attached, and is also
> attached to bug 608961. If you have any general thoughts/comments, I
> would love to hear them, but please note the scope of the document.

Hi Omari,

Comments on the spec:

"1) When an image is opened with no associated color profile, we assume 
that it is encoded in sRGB space."

I don't think we should assume that, do you have an example use case 
where that is a good idea? Speaking of use cases, we should document 
somewhere what uses cases the solution must support. If we don't 
document this then there will be use case regressions when the system is 
adjusted later.

I think we should rather assume the image is in the working space color 
space. My thinking is that it is the same working space color profile 
that is used for the GIMP color picker and also for images without a 
color profile attached. So when you pick RGB 128,128,128 in the GIMP 
color picker and open an image with no color profile, RGB 128, 128, 128 
in the image will be displayed the same as RGB 128,128,128 in the GIMP 
color picker.

"2) When an image is opened _with_ an associated color profile, the user 
will have the following options:"

I don't think I follow completely, why would we ask the user what to do 
here? If the image has a color profile attached, we should definitly use 
it. If the user wants to convert to some other color space for some 
reason, he can do that when he pleases

"3) When a PNG is opened that is tagged with the sRGB chunk
   a) This is as-yet undecided.  See the later discussion about sRGB 
chunk vs. sRGB profile."

If the image is specified as in sRGB, why should we not treat it as such?

"4) When an image with an explicit profile is exported
   c) If the file format has no way to embed color profile information, 

In terms of a problem, this is pretty similar to "when an image has 
several layers and we export to an image format that does not support 
layers, what do we do?". If the image doesn't support any kind of layer, 
we simply merge or flatten the image, no questions asked. If the image 
supports both layers and non-layers (such as animated GIF), we let the 
user choose. I think we should do the same in this case: if the target 
image format does not support color management whatsoever, we should 
just write the RGB values verbatim, i.e. do the best of the situation 
without becoming annoying and asking questions. If the written RGB 
values are important than the user needs to do a color space conversion 
before exporting into that format.

  / Martin


My GIMP Blog:
"Multi-column dock windows and 2.8 schedule"

Gimp-developer mailing list

Reply via email to