Question about Gamut checking

I have a question about the gamut checking toggle button.
To start with, I am using the rec2020 softproof and histogram profile, display and preview display are “system display profile”
I was processing a photo of some flowers. This is a screen shot of my darktable darkroom screen.

If I toggle the gamut checking, I get this.

And if I export to a jpg in srgb I get this.

I don’t seem to be loosing any detail in the centre of the flowers, so I wonder what the gamut checking is telling me. I know from some previous discussions that I should’t bother about checking gamut if what I see on the screen looks good, and I am on board with this. I am just curious to understand what is happening and if I should make some changes to my settings.


What gamut setting are you monitoring ?? Saturation?? Luminance??


What operating system are you using?
Also: what is your system display profile actually set to?
Is it managed?

Have fun!
Claes in Lund, Sweden

Good morning,
I don’t understand your questions, sorry.
For me the choice between saturation, luminance or any RGB channel are for the “toggle clipping indication button”, the one that is a square with the diagonal line.
The “toggle gamut checking” is the triangle with the exclamation mark and has no options for clipping. I thought it just coloured the areas that are out of gamut with respect to the softproof profile : in my case linearRec2020.

The other question " what is your system display profile actually set to? … Well, I don’t know… isn’t it the system display? I have 27" IMac that is color profile with a spyder3. Does it matter for the gamut clipping?

Sorry for my ignorance, I am here to learn.
Best regard,

I’m not too familiar with the darktable behavior, but something to consider is that, for the software to assert some pixel is out-of-gamut, it needs to know what the destination colorspace will be. Then, “out of gamut” means, “not in the destination colorspace”.

For display, to make this work properly, you need a display profile registered with the software that closely represents your display’s color capability (gamut). That’s the consideration @Claes’ questions are addressing.

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Ok, i understood that out of gamut was calculated between the colour coordinates (in XYZ) and the working profile (linear rec2020), not with the display.

I guess I’m going to have to read up on what darktable is doing, as that doesn’t seem useful to me. Knowing what is out of gamut with respect to the working profile isn’t what you are ultimately looking at.


I think there are some corrections coming…the thread of 3271 is very interesting esp to see even how those working on the software needed to work it back and forth to come to an agreement…

Actually not…check the links that I provided…currently there is a bit of a weird path going through the display profile and back to the histogram profile…