Hello guys, I’m new here. I started to learn Darktable following Boris Hajdukovic’s epic channel. I go step by step replicate what he does in the video. I downloaded the Sobotka’s raw file and applied AgX. However, the instant result in default is completely different than the Boris got in the video https://youtu.be/ZFGxdb2pH8g?t=1076
Any ideas please what I could have wrong? Thank you for help.
Hello @Channas and welcome to the forum!
Darktable uses a much larger color space than the graphics. You must select Rec 709 RGB or sRGB in the “input color profile.”
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Why not linear Rec2020 RGB, which is the default and AFAIU covers a wider gamut?
The name indicates which color space the graphic was created for:
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Thanks!
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This is it. Thanks Boris!
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You do understand it was for demonstration purposes, and not a recommendation, right?
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How do you mean? To change the input colour profile to sRGB?
Yes. It was done in this demo to show the “Notorious 6” effect more clearly. The same could have been achieved by setting the base space to sRGB on the primaries tab.
In general, when working with difficult lighting such as LEDs, larger spaces work better. They act as if you used higher attenuation, and avoid early ‘pushing’ of out-of-gamut colours inside the gamut, which may lead to artefacts.
Yes, thanks, I just had not understood why especially that color space was being used.
The “notorious 6” effect is diminished when colours are not fully saturated. A fully saturated Rec 709 colour is relatively less saturated in a larger spac, such as darktable’s default Rec 2020.
A consequence of this is, if you use the built-in presets:
- if the preset is set to use Rec 2020, and you switch it to Rec 709, or
- the preset is set to use the working space, and you set your working space to Rec 709 / linear sRGB / Adobe RGB (something smaller than Rec 2020),
you will have to increase the attenuation to achieve a similar ‘path to white’ effect (and increase purity boost to restore saturation in mid-tones).
Conversely, if you use something even larger, such as ProPhoto or Elle’s AllColorsRGB, a smaller attenuation / purity boost will suffice. However, not that those spaces can produce non-existent ‘colours’ (they have RGB triplets that are outside the spectral locus; they do not correspond to any real colour visible to us).
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