thank you. I am using lightroom. My discussion of photoshop only refers to what I know from reading and I do not really use it. I guess I need to spend time in it. It seems to be able to do what I want based on your clear reply.
Since you clarify that you’re using Lightroom, I’ll chip in. While curves adjustment layers with masks in Photoshop is probably the most flexible and direct way to achieve what you’re after, you can also get a “a lot of the way there” in Lightroom. Using your cloud example, use the paintbrush tool to create a selection that includes your clouds. Then use the range masking tool to narrow your selection to clouds (luminosity range masking most likely for clouds). You can then use a combination of tools;exposure, clarity, blacks, whites, contrast, etc. to take your selection in a lot of useful directions. I’ll often neutralize all of the sliders, and then turn on the visibility of the selection (the O key toggles) and create the selection first. Then when I’m happy with the selection, I’ll start to tweak it.
This approach is a sort of kluge, but you’ll be surprised at how well it can work as a “fake” selective curves adjustment.
I posted a query recently wondering why Adobe hasn’t given us true layers and curves in the targeted adjustment tools. That would be slick.
If you’re a member here, check out the Masters videos w/ Charles Cramer. He uses curves adjustment layers/masks to great effect in Photoshop. The videos are very instructive.
Rand