Hi, one of the things we dicussed shortly at GIMPCon was how to add basic color management to GIMP. We know that it will be a major effort to integrate this and it will need GEGL to do it properly. However there are a few things in this area that we should be able to do for GIMP 2.2. That should help users that are waiting for these features and it should help us to get some experise in this area. So here's the plan...
We agreed that lcms (http://www.littlecms.com/) seems to be a good choice for our needs. We already use it for the proof display filter so it's basically already a dependency and the plan I am going to outline is not going to make it a hard dependency. So if anyone wants GIMP w/o color management and w/o a dependency on lcms that will continue to be possible. There are a couple of things we want to to achieve: (1) color-correct the image display according to a monitor profile (2) make it easier to do soft-proofs (3) use color profiles embedded into files we open (4) embed color profiles into files we save (5) do color separation based on color profiles ... How much of this will make it into 2.2 depends on how much work is put into this which in turn means that it depends on your contributions. Some parts can be achieved by means of modules and plug-ins and can thus be developed further after the GIMP 2.2 release. We should now focus on the changes to the core and to the libgimp and module APIs that we need to get this done. I will try to propose some ideas that aim to implement the points mentioned above: (1) color-correct the image display according to a monitor profile This can be done rather easily using the existing display filters architecture. What stands in the way here is that display filters are not very well integrated yet. As a user you should not have to configure the monitor profile for every image display you open. So what needs to be done here is to improve integration of color display filters. Mitch and me already started to make some changes that are supposed to lead to a set of global display filters that are configured in the user's filterrc and that are loaded by default. The user can then configure a monitor display filter that color-corrects all image displays for her monitor. We will have to extend this to previews and color selectors in order to provide a consistently color-corrected user interface. (2) make it easier to do soft-proofs We have a display filter already that does soft proofs. At the moment it is however rather akward to use. I see two ways to improve this. One is to make it remember it's configuration and we are already working on providing that functionality for all display filters. The other improvement I see is to adapt to standard locations for color profiles. The file selector for color profiles should contain bookmarks for the default locations for color profiles as they have been suggested on the OpenICC mailing-list on freedesktop.org ($prefix/share/color/icc and ~/.color/icc). Perhaps we even want to add a special widget to select color profiles? (3) use color profiles embedded into files we open When an image file we open has an embedded color profile we should ask the user if the image should be converted to linear sRGB (which is what GIMP assumes internally). This will need changes to a couple of plug-ins and these changes need to go into #ifdef's since we don't want to depend on lcms. Or should we just add this dependency? (4) embed color profiles into files we save Not sure how much sense this makes. If we had a widget to select color profiles, then it would be easy to add ways to attach color profiles to images. I am just not sure if that makes sense for us since we can't (yet) work in the color spaces defined by these profiles (expect for the linear sRGB profile). (5) do color separation based on color profiles There are two plug-ins that can do color separation based on color profiles. One is the separate plug-in: http://www.blackfiveservices.co.uk/separate.shtml The other is the TIFF plug-in by Kai-Uwe Behrmann. I haven't looked at it recently and don't know what state it is in. But AFAIK it also does color separation to CMYK. I have some sentiments against including a plug-in with lots of #ifdef'ed code that is supposed to work for various flavours of GIMP as well as CinePaint but it would certainly be good to evaluate if and how this plug-in could replace the current tiff plug-in. Since I am not a color management expert myself, there might be fundamental design flaws in the stuff I outlined above. Please let me know about them and please contribute your ideas. Sven _______________________________________________ Gimp-developer mailing list [EMAIL PROTECTED] http://lists.xcf.berkeley.edu/mailman/listinfo/gimp-developer
