[Gimp-user] color.org

[<tz20 gmx de>]

On Mon, 09 Apr 2018 19:29:16 +0000
gimp-user-list-request gnome org wrote:

> hi gabriele,
> color management has been a mystery on many a list. i had a discussion on
> the scribus list many years ago when i mentioned my solution to my color
> management problems. i was told i was wrong, that i needed to calibrate all
> of my hardware and make a profile of each. i was a photojournalist in a
> former life and i teach photography with emphasis on light and lighting and
> color temperature.
>
> when i first embarked on my color theory journey, i was designing brochures
> and flyers as a freelancer for a company in new orleans, la that did
> meeting and convention planning (as well as designing their web site).
> after much research and question asking, i lit upon color.org. i went there
> and downloaded 2 color profiles (sRGB_IEC61966-2-1_no_black_scaling and
> SWOP2006_Coated3v2). i later ran across a cmyk profile when i used linux
> and saved that profile. these color profiles have the same d50 color temp
> (5000k). with progress, the rgb profiles at color.org are at version 4; i
> have not tested these profiles.
>
> here are my hardware and software setup for my systems (win, mac and
> linux). i copy the two color profiles to the appropriate profile folders
> according to the os and set them as the default color profiles for the
> system. then i set the rgb and cmyk profiles as default in all of my
> graphic software. i also set the rgb and cmyk profiles as default to
> printers, scanners and other hardware attached to the system that uses
> color profiles.
>
> i will usually make a "straight" print to preview what changes in color,
> exposure, shadow, mid-tone and highlights need to be made. i have found the
> color does not vary much from what the thumbnail on the screen presents.
>
> i would be happy to provide these profiles to you or anyone else on the
> list if you send me a private email; unless, the administrators will allow
> the attached profiles.
>
> i would be interested to learn if your results are similar to mine. there
> is much more to color management that i did not say to the argument that
> was raised on the scribus list.
>
> i hope this helps you find your way on your journey in the land of color
> management.
>
> many greetings
> kdd
>
> On Thu, Mar 15, 2018 at 4:46 AM, Gabriele Piccini <dafrasaga gmail com>
> wrote:
>
> > Hi All,
> > I think I'm wrong when I print from GIMP because I have a very yellowish
> > print....a very yellow color cast in neutral zones.
> >
> > I created a printer profile with ArgyllCMS and seems it works well because
> > if I test it with xicclu command (for who known Argyll) with neutral Lab
> > values I got neutral values (Lab->RGB output->Lab).
> > The issue arises when I print but I think to make a wrong way:
> >
> > Ok, what I did:
> >
> > I download a proof image from internet with Prophoto color profile.
> >
> > When I load in GIMP I keep ProPhoto therefore RGB device values are
> > ProPhoto RGB.
> > Then I convert the image into printer profile and I think the values are
> > converted to RGB values of printer profile based on Lab values of ProPhoto.
> >
> > Now I should have an image with device (printer) RGB values to send the
> > printer , haven't I? The printer if matches the ICC profile I created
> > should "translate" those RGB numbers into colors.
> >
> > But the image, I view correct on display is very yellowish on the paper.
> >
> > Is this workflow correct fro printing color managed in GIMP?
> > Or am I missing something??
> >
> > I do not know if I'm clear ( English is not my language ?)
> >
> > Cheers
> > Gabriele