war story: horrible colours on Seiki TV under Fedora 34
I updated to Fedora 34 on my desktop a month or two ago. Afterwards, everything on the screen had a horrible yellow cast. I couldn't get much help because I use the nvidia video drivers. Nouveau always goes sideways when I try it on this system, even though the card is old enough to be well supported -- GeForce 650. I fiddled about everywhere, half-heartedly, and just lived with it. - perhaps the in-place upgrade from F33 to F34 was botched. I installed F34 from scratch and had the same problem. So: no. - perhaps new Nvidia driver had a bug - perhaps chroma subsampling was botched (monitor supportss 4:2:2 at UltraHD resolution) - ??? Clue 1: when I moved the HDMI cable from the Seiki to a Dell, without taking the machine down, the Dell display looked yellow too. Clue 2: if I rebooted while connected to the Dell, the display looked fine. I did not try movine the HDMI cable to the Seiki after booting with the Dell. The Dell is a higher-bandwidth monitor and it's settings would not work with the Seiki. In the end, I discovered that the mysterious colour management system has a bad colour profile for my monitor. (It turns out that before F34 there was no colour profile for my monitor.) Under settings: Color, I selected the monitor and clicked right-pointing caret. Could see a profile called SE39UY04, which should be right for my Seiki SE39UY04. But it isn't. Added a profile, picking semi-randomly the Dell 2405FPW. It worked a lot better. I don't have the tools or the time to calibrate my monitor. The SE39UY04 was created by HP on 2018 Dec 20. I wonder why -- they have nothing to do with Seiki. This seems to be managed by colord, the color daemon. It seems poorly documented, at least in man pages. Profiles seem to live in two sqlite databases in /var/lib/colord. The following test shows both databases have entries for this monitor. grep -i SE39UY04 /var/lib/colord/*.db The same command on an old F33 installation shows no hits. So my problem boils down to the color management system learning about my monitor, but getting it all wrong. See <https://bugzilla.redhat.com/show_bug.cgi?id=1991561>
On 2021-08-09 8:52 a.m., D. Hugh Redelmeier via talk wrote:
I don't have the tools or the time to calibrate my monitor.
I'd be happy to lend you my ColorHug. Takes about 15 minutes. You will be amazed at how less blue everything looks, because vendors always set monitors for maximum brightness and coolness to wow people on the shop floor. cheers, Stewart
| From: Stewart C. Russell via talk <talk@gtalug.org> | I'd be happy to lend you my ColorHug. Takes about 15 minutes. You will | be amazed at how less blue everything looks, because vendors always set | monitors for maximum brightness and coolness to wow people on the shop | floor. That's a very kind offer. I may take you up on it once the plague is under better control. I'm suffering whiplash from the transition from yellow overload of the bad profile to the blue-forward of the Dell profiles. I don't really like to black-box nature of the profile presentation through the Gnome GUI. There should be some tool to examine and nudge a profile in useful ways. I'm tired of spelunking to find the right software tools for all these miscellaneous tasks. I wonder if Windows has a colour profile for this monitor. If so, can I turn it into something that Linux can use? Perhaps a .icc file is exactly that. I was OK with the previous state where there was no colour profile. Maybe I can go back to that somehow. I'm too lazy/backlogged/content to figure that out. I have a tremendous backlog of "should be easy but I don't yet know/remember how" tasks. One never knows how long they take until one has accomplished them. I lived with those horrible colours for over a month. My "war story" series is meant to document some of the victories. Perhaps I'm too prideful to post them earlier, in the unsolved state. I try to file bug reports when appropriate, even if I've solved the problem for me. This should be useful for all software but I consider it a duty for free software users.
On 2021-08-10 9:57 a.m., D. Hugh Redelmeier via talk wrote:
I don't really like to black-box nature of the profile presentation through the Gnome GUI. There should be some tool to examine and nudge a profile in useful ways. I'm tired of spelunking to find the right software tools for all these miscellaneous tasks.
Yes, there should. But there isn't one that I know of. Linux suffers from having two competing colour management systems. And each of them does one thing fairly well, but neither does all the things reasonably well. As far as I can see, lcms/lcms2 is the older system. It's almost all command-line based. It had an interactive monitor profile tool (lprof) but the developer abandoned it around 2002 and it hasn't seen any updates in 15 years. Argyll is the newer colour management system. It has some graphical tools, but none to nudge colour profiles. There are a bunch of complexities that might be affecting you: * Linux seems to be able to extract calibration information from the monitor EDID. The Asus monitor I'm using, despite me having a manual calibration for it, claims that the ICC profile was something it downloaded from the monitor. It may be that the downloaded ICC has applied any settings you've poked into the front panel, and Linux is gamely trying to correct for them twice. * Nvidia has its own colour calibration deal going on, apparently. It will quietly override any other system settings. (Some apps also have their own colour management: Firefox used to, but I think they fixed that) * The huge amount of effort in colour calibration is for process colour matching in printing. People get paid to get that right, and it can cost a lot of money to get it wrong. Monitors (under Linux, at least) are definitely second-tier. Don't get me started on scanner calibration ...
I wonder if Windows has a colour profile for this monitor. If so, can I turn it into something that Linux can use? Perhaps a .icc file is exactly that.
Yup. Windows ICM files = Linux ICC files. But a monitor with a few years' use on it will have shifted colour quite dramatically from a new one. I mean, it's not going to be the all-yellow you're seeing, but it may be difficult to get nice colours from it if you apply a factory calibration. cheers, Stewart
participants (2)
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D. Hugh Redelmeier -
Stewart C. Russell