youâre welcome. I moved from seattle to brittany so I know these skies well and have struggled with this exact problem for a long time!
Something that really pays off is to get very proficient at using the combination masking features in Darktable, as this is its real strength. For example, I suggested as a first step to desaturate everything - which really I should have said that we want to desaturate everything else except the greens, but I overlooked it trying to hurry.
To desaturate the image I used the global saturation slider in Color Balance RGB. The important bit about this module is that it makes edits in linear color space - which is a fancy way of saying that itâs more difficult to abuse the tool. Making a few subtle edits by masking off different parts of the image and duplicating this module to work on each section will tend to work out better than making an aggressive pull on a more âwildâ tool like the older saturation slider bar in the CSB module. Already the Color Balance RGB tool has a lot of granularity built into it, permitting one to make separate adjustments for shadows, midtones, and highlights. It is a very clever piece of software that is unique to DT.
Back to the mask:
Desaturating all of the other colors except our foreground greens should help to separate them just a bit. Before re-saturating them with the methods I first described, it would be helpful if we donât kill what color is already there.
Using the parametric mask first (the circular icon in the middle), go into the âhzâ - or hue - section of the JzCzhz color filters where we can select all the greens. Make sure you have the square icon selected to show the mask.
The top arrows set a hard mask, meaning that no colors will appear that are not between the arrows. If you lock the top and bottom arrows together and drag them inward, most often this is too harsh and will leave you with artifacts in the image after making adjustments. Thatâs what the bottom row is for, and adjusting the bottom row of arrows will feather off the selection so that we have a gradient in our selection and not a hard edge. (This works the same wherever the slider tool appears).
Here Iâve feathered it all the way back to the reds to preserve some of the color in the flora in the bottom right, but then constrained it heavily on the right side to suck out all of the blue tones from the sky.
You might ask why I didnât just go over the G tab of RGB: and the reason is that it we select the greens using only this tool, we will risk clipping the blues and reds attached to our foliage, which is undesirable. Likewise we could use the Gray sliders to select the tones - but on a gray day this will select big chunks of the sky, too! Hue tends to work out best for isolating foliage and trees. If there is a lot of tree bark showing, youâll want to let those left sliders include the yellows and orange huges as well to make sure theyâre selected.
This is looking pretty good, but now we want to refine the mask using the brush tool to eliminate all of the noise in the sky and the dam.
Using a fairly large brush, just select the bottom part of the mask that we want to keep. Iâve eliminated the valley floor in this instance to try and get contrast between the foreground and the desaturated valley; this is to taste, obviously! Your initial version with a verdant valley floor is a bit wild more my tastes but itâs also going in a nice direction.
Last masking step
You see in our selection that we have a lot of black dots. If our edits are aggressive, this can lead to bright lines between parts of the image that is masked and where it isnât - so to avoid this it is very important now to use feather radius to further smooth out the mask as a last step. I tend to be aggressive with the feathering radius. Here Iâve settled on ~ 90px. You can see that we now have some of our valley floor and a bit of the water selected, too.
This is not to worry: just select the line where we drew the mask and there you will see small squares. Click on the square closest to our overrun with the mask, and just pull it back. Another quick way to make the painted selection smaller is to hover over the line and while the squares are showing, then use your mouse wheel to increase or decrease the size of brush. This will save you a alot of time when masking.
Donât forget: each time you perfect a painted mask, it can be reused in any other module.
Final thought
The idea in this method is that we donât want the colors in the rest of the scene to compete against the foliage for attention, without having to over-saturate those tones to get them to stand out. If itâs raining or if the vegetation and foliage is wet, it will already be plenty saturated - especially with just a glimmer of sunlight. We want to add just a little bit without having the colors go wild and look unnatural. Every scene is different, and I never use presets preferring a basic approach like this to edit an image. The same settings donât work on every photograph.
If anyone else has tips or variations that work for them, Iâd be happy to hear it as well. hope this helps, cheers