darktable channels

A few questions and ideas regarding channels in darktable.

  1. Is there a way to view each R,G,B channel individually in gresycale, for the currently displayed image? I know they can be seen in colour when hovering the mouse over parametric masks input or output and hitting ‘c’, but it changes back to normal view as soon as you click away. Be nice if there was a little button, perhaps under the image by the toggle softproofing icons, to view each channel individually. If it already exists, can someone point me where.

  2. Is there a way to blend modules in each channel individually? Eg. I boost ‘exposure’ to +3ev, then slide input or output parametric mask in both R and G channels to 0, with the intention the adjustment will only affect the B channel. But I turn the exposure module on and off and nothing is happening, so it appears to have been taken out of all three channels, not just the two I turned down. Tried in Filmic module and same thing happened. Some may say the answer is to instead use blend mode ‘blue channel’, but if we wish to only boost exposure in the luminosity of blue channel we can’t do it, because we need the ‘lightness’ blend mode for that.

  3. In the channel mixer can we get the sum of each three sliders per channel, so we know when they = 100%?
    Two other ideas:
    a) A checkbox linking R,G,B to 100%. So if the box is checked, I’m in R channel and drag R down to 60%, G and B automatically rise to 20% each. Or if I drag G up to to 60%, R and B automatically lower by 30% each.
    b) Checkboxes to link two sliders proportionally. Eg. R/G, R/B, G/B. So if R/G is checked and I increase R by 20%, G will decrease by 20%, or vice versa, whilst leaving B alone.

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