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 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