I'm an Avid editor trying to learn grading with DaVinci. I've read and watched some tutorials, and have learned some basics.
But one thing I started to wonder about, I haven't been able to find the anser to:
What the difference between using the luminance only knob and the wheel, when adjusting lift, gamma and gain? And when to use which?
I use Avid Arist Color.
There are a number of books that look at this distinction, and I think the luminance control is discussed in the manual.
Fundamentaly, because nearly all image manipulation systems are based on RGB processing, making brightness adjustments becomes a challenge because its mathematically difficult to perform that kind of operation without affecting the overall matrix in some way that doesn't deviate from the desired effect in terms of balance, contrast, and saturation (at least perceptually, if not, in fact, numerically).
So luminance-only tries to offer an operating regime that simulates a Y'CbCr environment, in which the Y (luminance) component can be altered as if it was an independent channel -- which it might have been, but in this process is no longer. It could almost be regarded as a kind of secondary process, and it is not supported under any CDL protocol, becaause it is not, strictly speaking, an RGB process.
"I always pass on free advice -- its never of any use to me" Oscar Wilde.