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Peter Cave wrote:Horizontal wheel operates on all 3 colour channels (RGB) simultaneously and maintains the relationship between the channels so as to avoid any unwanted hue shifts. Y slider operates on a derived luminance math that adjusts the perceived brightness or luminance (not technical brightness which is the black level) while leaving the saturation untouched (not exactly but close enough). For those that need more explanation, use colour bars and scopes to see what is going on. It's quite obvious and using bars will quickly show how the relationship between these two controls works.
Yep, that is exactly right.
For practical purposes understanding the math behind the controls is not really necessary to achieve a good looking and technically correct image.
I think I said that and then got yelled at because they thought I was being condescending.
![:-O :shock:](./images/smilies/icon_eek.gif)
There are some fairly big-name colorists I know who are surprisingly untechnical. They worry only about how to take care of their clients and finish their shows effectively -- not so much how the math and science works under the hood. It's kind of like how a race car driver knows how to drive (very well), but probably doesn't know how to design or build an engine. I think it's two separate and distinct jobs. But it's always a good idea to have a basic grasp on what's going on in both directions.