In an old thread on LL which I found while researching enlarging-upresing techniques there was a reply from a member arsbbr (no longer active?) which I found both tantalising and cryptic in the extreme! Tantalising because I am on the cusp of a phase change in my approach to editing and the tipping factor will be learning a certain set of skills with layers and masks. Cryptic because arsbbr assumes that readers are already at that, for me, future point.
I put it here as I found and extracted it (btw its context was a thread discussing the tailoring of noise/grain for use in taming the artifacts created in interpolation during enlarging-upresing). I understand that 2 new layers have been created and each one contains a different curves adjustment (of the target image I suppose???). I understand that another layer contains the grain/noise. But how this grain layer becomes a mask (used normal and inverted) for the curves layers is where I go off the tracks! (Or perhaps the two curves layers are adjustments to the noise layer???) I understand that he is talking about tuning in both directions.
I have recently come across similar descriptions for applying effects through layer masks, and all of them have been similarly opaque to me. I would be very grateful if someone could unpack arsbbr's comments to help me grasp the basic technique he is referring to. Thanks.
Here is the post:
Clearly these two curves annihilate each other (which is mandatory) without layer masks.
One needs some appropriate layer masks. Appropriate means here that the mean luminosity value of the layer mask must be around 127. You can take scanned grain, artificially created etc.
Now just put the grain mask to one and the inverted grain mask to the other curve.
So now you have total control over the responding behavior of your artificially created film; you can add further control points, put the two curves in a layer set and control the strength etc.
All non destructive.