[Gimp-user] dilemma

[David Gowers]

Hi norman,

On Sun, Apr 6, 2008 at 8:13 PM, norman <norman at littletank.org> wrote:
>
>  > It sounds to me like norman does have color management, but his viewer
>  > either doesn't support it or color management info isn't being saved.
>  > To avoid these kind of problems, I convert the final image to the
>  > NativePC profile available at the following URL:
>  > http://www.aim-dtp.net/aim/download/aim_profiles.zip
>  >
>  > before trying to display it elsewhere.
>  > This ensures that it will display fairly normally even if there is
>  > some problem with color management.
>
>  Thank you very much for trying to help me with my image viewing
>  problems. The more I read the more complex things appear to get but I am
>  learning. However, could I return to the examples which started this
>  thread. We have constants and variables. The constants, for me, are the
>  hardware and the images, the variables are the software. The images were
>  produced by my son, using his hardware running Ubuntu 7.10, and Bibble
>  Pro, from RAW images I supplied, and were made available to me in JPEG
>  without any image size reduction.
>
>  I viewed these images using Eye of Gnome 2.20.1 (Image Viewer) which is
>  the default Ubuntu viewer, gThumb 2.10.6 and GIMP 2.4.2 with the
>  following results:-
>
>  gThumb and GIMP produced, as far as I could see, the same image but Eye
>  of Gnome produced an image that I can only describe as having more
>  punch. In layman's language the colours were brighter and the detail
>  sharper. Maybe I am just expecting too much but then, unless my son and
>  I use the same software to prepare and view our images, how can we help
>  each other to improve our photography?

Further points that might help:
a) GThumb does not support color management, so what you see in GThumb
should be typical of a non color managed display.
b) GIMP has a correctly color managed display... providing you have
the right profiles assigned. NativePC is a reasonable display profile
to choose if you have no monitor-specific profile. If the image then
does not display as you expect, then its profile is incorrect. Your
RAW processing software should allow you to assign a profile to your
image; GIMP also allows you to assign a profile and convert to a
profile.

Assigning a profile rather than converting to it can cause the types
of discoloration you describe. Only assign a profile if you are sure
that the image data is already in that format (eg. only assign a
linear profile if the image data is already linear.)

(however, if this were your problem, I expect you would notice it
immediately... UNLESS, as Sven suggests, you may have colour
management disabled. Check that it's enabled under View->Display
Filters, and consider altering the relevant part of the preferences to
'color managed display'

Hope that helps.