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Open Source Color Management Is Broken

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Re: Open Source Color Management Is Broken

#111

Post by [deleted] »

pvg wrote: post #96
ancientworldnow wrote: post #41

Earlier quoted context omitted.

I'm a colorist. Many of us do use windows, many use OSX, many more use Linux. Every major color critical application supports many types of LUTs and color management. Further, HP Dreamcolors have tons of problems and aren't considered solid for color critical work (but are fine for semi color accurate stuff like intermediate comps etc). Color accurate work is done over SDI with dedicated LUT boxes handling the color…

I'm a colorist This sounds pretty interesting. What do you actually do, in layperson-y terms?

[deleted]

Re: Open Source Color Management Is Broken

#112

Post by muzfuz »

pvg wrote: post #96
ancientworldnow wrote: post #41

Earlier quoted context omitted.

I'm a colorist. Many of us do use windows, many use OSX, many more use Linux. Every major color critical application supports many types of LUTs and color management. Further, HP Dreamcolors have tons of problems and aren't considered solid for color critical work (but are fine for semi color accurate stuff like intermediate comps etc). Color accurate work is done over SDI with dedicated LUT boxes handling the color…

I'm a colorist This sounds pretty interesting. What do you actually do, in layperson-y terms?

Sit in darkened rooms, spin 3 trackballs, and turn a few knobs to make pictures look pretty, mostly. DaVinci Resolve[1] and Baselight[2] are quite popular, take a look at the websites to give yourself an idea of what it looks like.

1. https://www.blackmagicdesign.com/products/davinciresolve/

2. https://www.filmlight.ltd.uk/products/baselight/overview_bl....

Re: Open Source Color Management Is Broken

#113

Post by jacobolus »

muzfuz wrote: post #110
jacobolus wrote: post #105

Earlier quoted context omitted.

Everyone needs to characterize (not “calibrate”; that term is highly misleading) their display. The question is just whether you keep the characterization provided by the manufacturer, or measure the display yourself using a hardware device. Either way, the result is a display “profile”, which is basically a lookup table used by software to map color coordinates so that they will appear as expected on the display. Pe…

In many professional environments the preferred route is to use specialist hardware to send an RGB signal at a high bit rate and do any colour transformation in the monitor hardware. Using LUTs either at the application or OS level to adjust colour information is a big no-no, although that doesn't stop some people from doing it. You simply don't want to change your colour space[1] until you absolutely have to. The po…

If you have some image data stored with reference to one color space, and you want to convert the data to a different color space (e.g. because you are targeting some particular output device), that is a gamut mapping problem. To learn about different trade-offs involved in choice of gamut mapping algorithms, I recommend Ján Morovič’s monograph, https://www.wiley.com/en-us/Color+Gamut+Mapping-p-9780470030...

Same story if you want to show your image on a display with a different gamut.

Most gamut mapping algorithms used in practice (whether on a display or in software) are actually pretty mediocre in my opinion. It would be possible to do substantially better by writing your own code, at the expense of being a bunch of work. Alas.

P.S. The Wikipedia article about color space (and articles about many other color-related topics) is pretty terrible, but I’ve been too lazy to rewrite it.

Re: Open Source Color Management Is Broken

#114

Post by dm319 »

ancientworldnow wrote: post #89
dm319 wrote: post #85

Earlier quoted context omitted.

you might want to see the post further down with the technical details (possibly ended up in the wrong place)

Yeah that's exactly what happened. Mobile client glitched, but it's in both places now.

Your work sounds fascinating. I was previously into my photography, specifically film (both slide and col neg) - I'm still a big fan of the medium, except for the expenses and faff of getting a good scan and then getting the colour right.

Can you help me answer two things, as both have bugged me for years..?!

How do they achieve a look of tinted monochrome in films, which are still actually in colour? If that doesn't make sense - I'm thinking of films like Heat where there is often a strong blue tint which gives the feel of monochrome but it is all in colour. I've found was able to replicate it somewhat by combining the image with a quadtoned version, but it was still fairly far off tbh.

The other question is - how does colour gamut relate to the brightness of the display? Is it all to do with the dynamic range of each channel - i.e. the difference between black and, say, red, rather than overall brightness? I was at a photography show recently, and was blown away by some of the prints made by some of fuji's printers. Is it ever possible to match the gamut our eyes can see? And what colour space/gamut do you usually work in? Sorry two extra Q's there...

Thanks, and thanks for the fascinating info already.

Re: Open Source Color Management Is Broken

#115

Post by newnewpdro »

newnewpdro wrote: post #109
braderhart wrote: post #102

Earlier quoted context omitted.

Yeah... I think both are applicable, but if you really want something done then you do it yourself or pay someone to help do it, especially for open source. It sounds like have a descent idea of where to start. I'd go find some kernel developers working on the underlying components, and offer to pay them or see if they have recommendations of people to get the work done.

In doing some searches on the subject this [1] came up. So there seems to already be movement on this front, and it's possible my knowledge of the current situation is stale. [1] https://lists.freedesktop.org/archives/intel-gfx/2015-Septem...

There's definitely some level of gamma/color correction funtionality at the DRM level already in the kernel [1]. So my desires may already be largely fulfilled, and maybe userspace just needs to get its act together.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/lin...

Re: Open Source Color Management Is Broken

#116

Post by fro0116 »

ancientworldnow wrote: post #86
anfractuosity wrote: post #82

Earlier quoted context omitted.

Awesome, thanks for the heads up :) Just for curiosity what manufacturers make the very best monitors in your eyes for colour work?

Flanders Scientific, Sony, Dolby in order from cheapest to most expensive. FSi and Sony use the same panels for their 25" models. Sony x300 is the go to right now for affordable HDR. Dolby is the gold standard for non projector color critical work. For non color critical necessary displays, Eizo is about the best. Lots of" good enough" panels from LG, Acer, and Fell though. I actually have a gaming panel that calibra…

I don't have any experience with the more expensive panels you listed, but I do have an LG OLED, and I'd be a bit more careful about recommending it for color critical work as a computer monitor.

I've owned it for about a year and the red channel on mine exhibits painfully obvious burn-in patterns.

Re: Open Source Color Management Is Broken

#117

Post by Nexxxeh »

ancientworldnow wrote: post #83
pzone wrote: post #50

Earlier quoted context omitted.

That's not right - Linux is used on desktop workstations as well. Check out the discussion in this recent thread. https://www.reddit.com/r/linux/comments/7zms77/gnome_2_spott...

So this is about DaVinci Resolve since it has the most flexibility for setup, many other systems are borderline turnkey. The recommended setup is a super micro chassis with dual xeons (12 core cpus min rec, 20 core preferred), min 32GB ram (usually at least 64,128+ common on high end systems), SSD for OS, thunderbolt (min)/pciE/10GbE/fibre (preferred) attached storage usually 8 bay raid6 or similar min, almost always…

Are the ports on the 1080ti's used for video output at all? Is there one with SDI out? Or are they just used for CUDA?

At the risk of asking a silly question, what does the LUT-box do that couldn't be done in software (or, I guess, why isn't it done in software)?

This stuff is fascinating to me.

Do you know of any good YouTube videos on colorist hardware? I've seen a couple of videos on workflow, but neither went into the guts of the machines and LUT-boxes.

Re: Open Source Color Management Is Broken

#118

Post by gsich »

coldtea wrote: post #53
giovannicarruba wrote: post #42

Earlier quoted context omitted.

Did you just assume my color space preferences?

No, parent just asserted that there are no "color space preferences" (outside of accessibility) people should have, period (and if they do have, OS/software makers and monitor companies should be OK to ignore them).

That was a troll...

Re: Open Source Color Management Is Broken

#119

Post by bitwize »

borplk wrote: post #90
cratermoon wrote: post #9

The Linux community will attempt to solve the problem by attempting to create an entirely new color management system, which will get at best 80% done with a handful of outstanding Hard bugs, at least one of which will be bad enough to break the entire thing except on one specific distro/gui/hardware combination.

It will just be a sub-component of systemd. Named colord.

Hackernews will tell us that we should really be using Wayland, because Wayland will solve the color problem once and for all.

When it comes time to implement the color management stuff into Wayland, it's declared out of scope for the core Wayland protocol, but don't worry guys -- someday, somehow, a consortium led by GNOME will implement it on a DBUS interface that all compositors will understand. At least two, mutually incompatible, such protocols emerge, neither of which fix the underlying issues, both of which are tied to particular compositors.

Meanwhile, we are told that X11 is still horribly, irredeemably broken in this regard and if we haven't yet switched to Wayland, we really should by now.

The professional colorist industry goes on using Xorg on Linux.

Re: Open Source Color Management Is Broken

#120

Post by foepys »

fro0116 wrote: post #116
ancientworldnow wrote: post #86

Earlier quoted context omitted.

Flanders Scientific, Sony, Dolby in order from cheapest to most expensive. FSi and Sony use the same panels for their 25" models. Sony x300 is the go to right now for affordable HDR. Dolby is the gold standard for non projector color critical work. For non color critical necessary displays, Eizo is about the best. Lots of" good enough" panels from LG, Acer, and Fell though. I actually have a gaming panel that calibra…

I don't have any experience with the more expensive panels you listed, but I do have an LG OLED, and I'd be a bit more careful about recommending it for color critical work as a computer monitor. I've owned it for about a year and the red channel on mine exhibits painfully obvious burn-in patterns.

I don't know why you are being downvoted so hard. Red is a very complicated color on OLED displays and manufacturers admit that frequent calibration is not only necessary but will eventually kill the display after a few years.
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