Very confused with color management and profiles

[priort (Todd Prior)]

“It would be great if there is a web page with the (more or less?) consensual things discussed here. There are zillions of pages about color management, rendering intents, etc, but few explaining carefully which is a recommended workflow for a photographer, specially a linux one.”

I think Glens link above is about as clear as you can lay it out. It seems its sometimes just harder to understand how all the software and hardware are playing ball together in this framework…

Also lots of great info and explanations found here It would be great if there is a web page with the (more or less?) consensual things discussed here. Overview of Color Management

[Luis_A_Florit]

Yes, I read that excellent page. Very nice analogy with peppers.

[Luis_A_Florit]

Thanks for the extensive explanation, Xavier. The only thing that it is not clear is this:

In short: if you wish to be sure about Chrome rendering about the same colors as Firefox and RT, you better use a profile with a standard sRGB TRC («gamma curve»).

RT gives at least 4 sRGB output profiles:

1. No profile (default to sRGB). This is discarded from everything just wrote.
2. RTv2_sRGB
3. RTv4_sRGB
4. sRGB

Which one to use? Are you suggesting to use another one ?

[priort (Todd Prior)]

@XavAL

sRGB IEC 61966-2-1:1999

I think this is the most common std…WIndows uses it by default i think if I remember correctly…

sRGB IEC 61966-2-1:1999

sRGB

[kofa (István Kovács)]

In my naïve view, I think of histograms and colour pickers as measurement tools/devices.
I think normally I’d be interested in the following measurements:

• input or output of the currently selected module, in the respective colour space (normally, the working space, except for modules that perform colour space conversion; but I think normally one would ignore those, as it’s the processing modules we’re interested in). Input is, of course, always the output of some other module, so this can be simplified to output of modules only. This is like measuring the signal at some point between stages of an amplifier or whatever;
• output after the output colour space conversion (the data that will end up in my exported file, sans compression artefacts). That is like measuring the final signal (using a strictly resistive load - but I don’t know enough about electrical engineering, so I’ll stop).

Involving the display profile makes little sense. One rarely judges amplifiers by placing a microphone in front of the speakers.

[ggbutcher (Glenn Butcher)]

@Luis_A_Florit

RT gives at least 4 sRGB output profiles:

1. No profile (default to sRGB). This is discarded from everything just wrote.
2. RTv2_sRGB
3. RTv4_sRGB
4. sRGB

Which one to use? Are you suggesting to use another one ?

Use the RTv2_sRGB. Version 4 profiles are not yet widely recognized in viewers.

[XavAL (Xavier Bartol)]

@Luis_A_Florit

Which one to use? Are you suggesting to use another one ?

Sorry I didn’t explain it better. If you haven’t read the discussion I referred to, a color calibration device is needed (in my case an i1 Display Pro) to create a custom display profile.

If you don’t have one and don’t have any friend who can lend you one, then I guess (and it’s only a guess) that your best bet would be setting your display into sRGB mode, calibrate as best as you can your display (means playing with the buttons of your display to get decent contrast and brightness; there are online pages to do that), and set sRGB as your display profile system wide and/or your applications.

Then you would export images with sRGB as output profile.

@priort

I think this is the most common std…WIndows uses it by default i think if I remember correctly…

Yes, that’s what I was trying to say.

But if you read the page on that link, you will see that it lists the specs, though you can’t download the profile itself. In their download page they offer you the 2014 v2 version of the profile, which I was shown some time ago to be a bit glitchy.

@kofa

I think of histograms and colour pickers as measurement tools/devices.
…
Involving the display profile makes little sense

Using the appropriate button in RT () you can switch readings between working profile and output profile. Those readings are used to draw the histogram (either the working profile with a sRGB gamma curve applied, or the output profile with its own gamma), and to show pixel values in the area below the navigator window.

There’s nothing regarding the display profile there. But as you may understand, to actually render the image on screen, a display profile must be used, or the colors you see would have nothing to do with the real colors in the processing engine or in the output image.

So involving an accurate display profile makes all the sense, because without it you wouldn’t ever successfully edit an image, as you would not see the correct colors. «Aside from this», the display profile is not used in your image.

Think about judging your amplifiers with the light on (with a display profile), or in complete darkness (without display profile). The light is just an aid, but is absolutely needed.

[kofa (István Kovács)]

I was referring to darktable’s behaviour.

[heckflosse (Ingo Weyrich)]

Honestly, that wasn’t clear, as this thread is about darktable, gimp and rawtherapee…

[Soupy (Tim)]

@Luis_A_Florit

My understanding is that softproof is to see how the image will look in other profile than the one we’re editing. Specially for printing.

Yes, and primarily to see how it will look when output to a device/platform with a different gamut. But if your output profile is srgb, and you soft proof srgb, you will see no difference.

@Luis_A_Florit

Even if I see lots of clipping in sRBG and no clipping in rec2020 (my working profile), I don’t see any difference in the image, only in the histogram.

This is because what you see is limited by your monitor gamut. If your monitor can’t display more than srgb, then you will see no or only small difference between the two.

[kofa (István Kovács)]

Sorry about that. I assumed that display profile being part of the chain from image to histogram would imply that I’m talking about darktable; but I should have been more explicit about that (there’s the famous catchphrase about assume making an ass of U and me). Sorry, @XavAL, for making you write an even longer explanation.

[Luis_A_Florit]

Indeed, got it.

Thanks to all for all the information!! I learned a lot from this thread, and my workflow is now better configured.

[Peter]

I am having similar issue. I have calibrated my Dell display.

I always export for sRGB when publishing for the web. sRGB should look the same or at least very similar, but for me sRGB looks too much vivid. If I activate soft proof sRGB I will get darker shadows. That seems fine for me. But when I export to jpg with sRGB it is not close at all to the soft proof profile.

The only way for me to see what the exported picture will look like is to change display profile to sRGB.

Which one looks best below with the colours, if your display is able to show both AdobeRGB and sRGB?

Adobe RGB

sRGB

[Thanatomanic (Roel)]

@Peter

I have calibrated my Dell display.

To what standard? It matters if you calibrate with sRGB as reference, or something else.

In any case, for a properly calibrated display, leave the display profile and preview display profile on ‘system display profile’ if you want accurate color representation.

It was my understanding that if you turn soft-proofing for sRGB on, and you are sure the sRGB profile is embedded in the exported file, and you view that file in a properly color managed application, it should look identical to the preview in darktable.

[Peter]

Calibrated to AdobeRGB.

The exported jpg with sRGB looks good in all properly colour managed applications on my computer, but for devices that are not the colours look way too saturated.

If an exported jpg has sRGB, why would it look more saturated in for example Firefox with Full Color Management set to 0 instead of 1? And Shotwell in Ubuntu, is it even possible to colour manage that one?

I will later upload a couple of sRGB photos to show, just to get a second opinion if the pictures are too saturated or not.

[priort (Todd Prior)]

If its an old monitor does it even support Adobe RGB colorspace??

[priort (Todd Prior)]

I may not be totally following what you are doing but from what you said things go darker in softproof mode when set to sRGB for softproofing. That might be expected if your display is set up quite a bit differently than sRGB . sRGB is now being used as your display profile when you softproof…you may need to add some exposure back and then your exports should look fine however when you turn softproofing off they will be too light using your display profile again…

[Peter]

I bought the screen just because of AdobeRGB. Dell U2413 if I remember right.

The issue is not that softproofing goes a little bit darker. The issue is that exported sRGB jpeg seems to be way over saturated in software like Shotwell. It is like Shotwell can’t read sRGB correct. My Samsung tablet, that can’t show AdobeRGB or 100% sRGB will also over saturate the colours.

If you export a sRGB jpeg and open it in Shotwell, how does it look compared to the one in darktable?

[Peter]

Seems I got a good explanation here https://www.reddit.com/r/linux/comments/kqyg55/experimenting_with_colour_managed_applications/

Anyway, a sample picture from me. How is the sky? Blue or green/blue?
IMG_6048_01.zip (7.1 MB)

[priort (Todd Prior)]

Looks good to me …fairly warm image…some cast in the horizon along the waters edge…but if if you remove the lighting from the rocks then the sky is unnaturally blue to my eye…