How to validate a calibration

[r.owe...@gmail.com]

Hi all,

I just received the Colorhug 2, and first of all I would like to thank Richard for the great product!

My color management situation is a little complicated: I'm running Arch Linux on a laptop with an external monitor, and StumpWM as my window manager, so I don't have the built-in gnome color management utilities. I have created profiles using dispcalGUI on the live USB stick, and am loading them when X starts using this line in my .xinitrc:

/usr/bin/dispwin -d 1 -I ~/.local/share/icc/Laptop_ArgylProfile.icc
/usr/bin/dispwin -d 2 -I ~/.local/share/icc/External_ArgylProfile.icc


Is there a way to verify that a particular application is correctly loading the profiles? For example, I would like to create a test image with some known RGB value, open it, and then be able to place the colorhug on the screen and read what the actual displayed RGB values are. Is there a utility I can use, sort of like a "real" color eyedropper using the colorhug?

The three applications I am interested in verifying are:
Firefox (images uploaded to facebook appear oversaturated, but that could be facebook misbehaving. I have set gfx.color_management.mode to 1 in Firefox about:config).
geeqie (images appear oversaturated and green-ish with color management enabled. Is relatively close to Firefox)
Darktable (Everything appears flat-er than in Firefox and geeqie, and I'm assuming Darktable is correct here).

Darktable ships with a darktable-cmstest utility, and when I run it I get:

LVDS1    the X atom and colord returned different profiles
    X atom:    _ICC_PROFILE (3621596 bytes)
        description: Screen 1 #1 2016-04-24 12-38 2.2 M-S XYZLUT+MTX
    colord:    "(none)"
        description: (file not found)

VGA1    the X atom and colord returned different profiles
    X atom:    _ICC_PROFILE_1 (1420944 bytes)
        description: E2414H #2 2016-04-23 00-22 2.2 M-S XYZLUT+MTX
    colord:    "(none)"
        description: (file not found)

Better check your system setup
 - some monitors reported different profiles
You may experience inconsistent color rendition between color managed applications

It seems like I do need to solve the fact that colord doesn't show any profiles (since I'm seeing incosistent results between color managed applications). If anyone has any suggestions that would be wonderful! If I could use colorhug to check whether darktable is displaying correctly would help sort out what is going on.


Thanks in advance for any suggestions!

-Owen

[v2g...@gmail.com]

Hi Owen -

Did you ever resolve this issue of <darktable-cmstest> returning: "X atom and colord returned different profiles."

If so, can you point me in the right direction?

Running Linux Mint 18.2 KDE. But to be honest, I've always had this problem after running dispcalgui and installing a profile. It seems like the profile is valid and running under Darktable but some other software is unaware of the profile. Anyway, it would be nice to resolve the issue. BTW: colord is now ported to KDE 5 (plasma 5) <https://dantti.wordpress.com/2016/10/21/colord-kde-0-5-0-released/>.

Thanks,

Bob

---

[stur...@lieberbiber.de]

Firefox defaults to only color manage tagged images (https://developer.mozilla.org/en-US/Firefox/Releases/3.5/ICC_color_correction_in_Firefox). geeqie seems to use the _ICC_PROFILE, as do some other applications. Some expect colord to be working, which is not the case in your setup. Most don't do any color management. I'm using XFCE as my desktop of choice, but I have found it most practical to switch to GNOME Shell every time I do serious image processing because it is the only Linux desktop with "foolproof" color management configuration. On Ubuntu Unity is also a viable option.

Were DisplayCAL/ArgyllCMS able to create good profiles for your displays? Laptop displays tend to have horrible color space coverage (less than 70% sRGB), but many monitors are also quite bad. DisplayCAL tells you the coverage after it has generated the profiles, and you can verify the calibration with the "Verification" option.