On Mon, 2008-02-04 at 21:08 +0900, Choi, JiHui wrote:
> Hi, list
> you know, GIMP 2.4 gives color management function.
> but I think GIMP can't recognize new color profiles automately like as
> brushes, patterns..
> I found all directory related GIMP, but I couldn't find color profile
> Of course I can add new color profile, using preference -> color
> management -> RGB profile -> select color profile from disk..
> However I want to recognize automately. how do I do for it? Or can't
Good luck in getting information about matters like this. The
documentation on gimp color management is sparse to non-existent. In
the fullness of time I expect this will be remedied, but it doesn't seem
as if it will be any time soon.
Are you using gimp under Linux or under Windows? I have no idea how
gimp color management might work under Windows. Windows does have some
standard locations where things like display profiles are put, but I
doubt if gimp makes use of them.
I have managed to work a few things out under Linux, but I am not at all
sure of them, so read with care.
Some color managed applications under Linux make use of the .color
directory in your home directory. I don't know if gimp does that.
There is an option to make use of the "system profile" for your display
profile, but I don't know what gimp does when you check that. There is
a way under X to specify a display profile, but I don't know if gimp
makes use of that. I've seen some suggestions that it does. You would
have to figure out how to specify that information to X. That is
something I meant too figure out, but I haven't got around to it.
With respect to displays, keep in mind that there are two issues
involved. When you calibrate/profile a monitor, there are two things
you do. First you calibrate. That involves some possible adjustment of
monitor controls, but it also may involve creating a look up table (LUT)
to be loaded into the video card memory to tweak the calibration. That
calibration information, if any, is stored in the display profile and
called the vgct tag.
In addition, profiling involves creating various transformations to
interpret the RGB values in your image file so that they will produce
the right colors on your monitor. The values in the image file are not
changed, just used to tell the monitor what to do.
So, first independent of what gimp may do, you need to load the LUT
information (the vgct tag) into the video card. That is done under
Linux by a program such as xcalib. In addition, gimp needs to have
access to the transformations in the profile, so it has to know where it
is. (I don't think gimp separately loads the vgct tag, but it wouldn't
matter if it did. In any case, you can test that with a little
experimentation.) It is probably best to assume gimp can't find the
display (monitor) profile by itself, so you should specify that under
Preferences. It won't matter then where you put it, but .color in your
home directory would seem appropriate.
Gimp by default uses the sRGB color space (profile). In principle you
could load another one either by embedding it in the image source file,
or, I think---but am not sure---by specifying it under RGB in
Preferences. You should be able to check what it is by checking under
Image>Image Properties>Color Management. I am sticking with sRGB
As best I can tell, gimp doesn't embed in its output any information
that a further application could use as a source profile. If there is a
profile for a color space included in the input image, say from a
scanner or digital camera, it appears that gimp leaves it there. It
would be safest to tell any subsequent application what to
use---presumably sRGB if you do as I do---but be sure you know what it
I've been told in this forum that if you switch in Preferences from
Color Managed Display to Print Simulation in the Mode of Operation, the
display profile will still be used if you specify one. This makes sense
because you presumably wouldn't be using gimp for print proofing without
using a display profile if you have one, but it can be confusing. The
gimp developers might consider altering the interface in the Preferences
window to clarify this. Better yet, they might consider moving the
choice of simulating prints somewhere outside the Preferences window
where it could be chosen, so to speak, on the fly.
There is no reason to believe that gimp can find a printer profile. You
would have to specify that under Preferences. In any case, it would be
used just for soft proofing, i.e., showing on your monitor, roughly what
a print would look like, and if you specify, which colors would be out
of gamut. Don't be panicked if a lot is shown to be out of gamut. A
printer profile is supposed to move color into the printer gamut, and
that sort of thing is inevitable. If you've done everything right, what
you see in the print should be a reasonable approximation of what you
see on the screen although few colors may be rendered exactly.
Gimp can't presently use a printer profile to print. To do that you
would need an external application which could use the source profile
(perhaps, as above, sRGB) and the printer profile as destination to do
that separately. One such application under Linux is photoprint, which
is still a work in progress and has very little documentation, either to
help you build it or to figure out how to use it. Still, if you can
work your way through that, it may be the best approach, since
photoprint will also do the printing for you. In a previous posting in
this forum, I explained an alternate ad hoc way to do it using some
other external programs available under Linux for dealing with the
profiles and gimp to print.
Don't take what I said as the last word on the subject. Someone may
object to some of what I said above, and that would be useful also.
> please, give me any answer.
Gimp-user mailing list