[GTALUG] war story: horrible colours on Seiki TV under Fedora 34

[Stewart C. Russell]

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