Open Source Coloration Management is broken

Open Source Coloration Management is broken

Since I’m now in the business of pictures and image processing (survey my commute pictures blog here), I believed it became time to lastly fetch lawful monitors and calibrate them. I wished to construct this with Open Source instruments and exercise the calibration recordsdata for my Linux desktop, so I ordered a ColorHug2 colorimeter, which is Open Hardware compliant and the total instruments are FOSS licensed. And from then on all the pieces upright went downhill.

The ColorHug2 comes with a little USB storage key which is presupposed to have a Fedora Stay Session ambiance with the total instruments to calibrate the show. The created ICC color profiles can then also be outdated-favorite on other devices (even on Dwelling windows and MacOS). Excluding that both my notebook computer and PC refused to even offer the key as a bootable tool (which looks to be to be a recognized scenario). Effectively, it uses the DisplayCAL GUI frontend for ArgyllCMS anyways, and both these programs are in the repositories of any smartly-liked Linux distribution. I had already outdated-favorite them two years ago to calibrate some devices at work, so I set the USB key aside, set in DisplayCAL on my devices, set up the ColorHug2, and started calibration runs. Simplest to gape ArgyllCMS fail every time time for the explanation that USB connection to the ColorHug2 saved failing after a whereas, which also looks to be to be a recognized scenario. Divulge. That is de facto no longer what I ask once I make investments bigger than a hundred € in an Open Hardware tool.

The recognized workaround for the scenario looks to be to be a further USB reset after the tool is released (pointing to a firmware computer virus in the ColorHug2), which is contained in the very most modern ArgyllCMS 2.Zero.1 beta pattern soure code. So I downloaded, built and set in it, and the calibration lastly ran via. However earlier than the calibration starts, DisplayCAL reveals an interactive show adjustment show to derive you put collectively the show as accurate as possible earlier than the categorical calibration starts. A piece colleague lent me his Pantone huey colorimeter, which also works with ArgyllCMS. My photo editing video show at home is a BenQ BL2711U, which is equipped as a talented 4K CAD Computer screen, has a hundred% sRGB color space protection and is recognized to derive very accurate color representation even on manufacturing facility defaults. So I expected both the huey and the ColorHug2 to gape upright minor deviations, and the measurements to be constant.

The DisplayCAL interactive show adjustment show.

Which became fully no longer the case. The dialogue reveals the distribution between the three color channels, and if the show has the foremost controls (laptops don’t), you correct until all three channels meet in the center. With the huey, AryllCMS detected a extraordinarily small green tint with the manufacturing facility settings, which I corrected by lowering the Inexperienced channel from a hundred to Ninety nine in the video show settings. The ColorHug2 measured a non-gift very heavy green tint, and I had to decrease the Inexperienced channel from a hundred to 80 to make the bars meet. At that point the total show had change correct into a rather heavy red (the Blue and Red channels being device overblown in comparability to Inexperienced), which positively wasn’t accurate. So I gave up on the ColorHug2 for the moment and persisted with the huey, but there are some indications that this could per chance also very smartly be one other ColorHug2 scenario. (I later chanced on out that there is a firmware update to model 2.Zero.7 for the ColorHug2, which easiest looks to be to be readily accessible throughout the fwupd tool, but no longer throughout the colorhug-instruments or from the repository the set the total other releases will be chanced on. I haven’t tried this update but.)

DisplayCAL/ArgyllCMS gave me a accurate profile the utilization of the huey and confirmed that the BL2711U primarily exceeds the advertised a hundred% sRGB protection. The distinction between the utilization of the calibration recordsdata and never the utilization of it became barely noticeable. Now I wished to derive the system and every software exercise my generated profile. Turns out the XFCE desktop I exercise simply doesn’t derive any color management, enjoy most other “smaller” FOSS desktop environments. That you just would be capable to per chance also exercise a tool enjoy dispwin to manually write the correction values into the video ogle-up desk (VideoLUT) of the graphics card, but the applications also must know relating to the profile so that they’ll story for it, e.g. when changing between color spaces (every browser has to construct this). And here is the set it will get primarily sophisticated: That is Linux, so there are no principles or requirements.

An example of the KDE color management settings show provided by colord-kde.

There are extra than one ways to mumble an software relating to the present profile. There could be colord, a daemon which will blueprint, store and set up calibration profiles and sensors and offers its services through D-Bus. And there could be the _ICC_PROFILE X11 atom, which permits applications to join profiles to and count on profiles from X.Org show outputs. Ideally colord would construct all the pieces, nonetheless it runs in the background and doesn’t derive access to the working X session, so it desires helpers. GNOME and KDE Plasma derive GUI frontends for this, and both kded and gnome-settings-daemon derive plugins for surroundings the _ICC_PROFILE X11 atom. Excluding that they easiest set it for the foremost output. Turns out whenever you happen to’ve got extra than one shows, the profile for the first one is set into the _ICC_PROFILE X11 atom, but the profile for the 2d one in the _ICC_PROFILE_1 X11 atom, for the third show in the _ICC_PROFILE_2 X11 atom, and loads others. It’s upright that no-one looks to be to construct this.

That ability your profiles could per chance also primarily be written into the VideoLUTs of the respective outputs, but every software which relies on the _ICC_PROFILE X11 atoms will easiest be ready to fetch the profile for the foremost show. darktable pleasurable worthy looks to be to be the most nice artful one available, due to it helps both _ICC_PROFILE and colord and to boot offers the pleasurable darktable-cmstest tool which will be outdated-favorite to have a study which surroundings is currently set to which designate.

Example output of the darktable-cmstest tool whereas working below GNOME Shell. Gaze that _ICC_PROFILE_1 and _ICC_PROFILE_2 aren’t set, whereas colord is conscious of the supreme profiles for all shows.

However it will get even worse. GNOME (and Ubuntu Solidarity, which borrows most of its instruments) no decrease than has color management built into the desktop ambiance by default. KDE Plasma offers kde-colord, nonetheless it’s an optional kit, and as an instance in Ubuntu 18.04 it’s four years musty, two releases in the support of and doesn’t work due to it looks to be to serene preserve we stay in a KDE Four world.  When you happen to exercise KDE Plasma on Ubuntu this day, you will also’t even derive color management. All in all here could per chance also be why many developers, in the occasion that they even care about color management, upright quit and let the person set the profile manually. This no decrease than looks to be to be upright for GIMP, PhotoFlow and RawTherapee. Firefox by default easiest does color management for tagged images. Chrome/Chromium, Gwenview and digiKam seem to make exercise of _ICC_PROFILE, but per chance easiest for the first show as smartly.

So these are my present suggestions for color management on Linux:

  • Make certain you primarily favor and wish it. As I’ve written the manufacturing facility settings of a accurate video show will be rather accurate already.
  • Ensure the applications you need color management for know what color management is. Most don’t.
  • Simplest exercise one show, otherwise it’s top to positively could per chance also are living with having color management on upright the foremost one.
  • Use GNOME Shell or Ubuntu Solidarity with X.Org. I don’t judge Wayland even has a specification on the supreme device to construct color management.
  • When you happen to primarily favor KDE Plasma, be sure colord-kde works. It’s miles broken on Ubuntu 18.04, but works shining on Arch.
  • Accumulate someone who lends you a working, expert-grade calibration tool supported by ArgyllCMS (it helps many) earlier than you spend bigger than a hundred € on something upright due to it has an Open Hardware decal.

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