Modifying Luma
 
 
 

While working on luma, you can modify the R, G, B, saturation, and luma along the luma range.

You can toggle the Red, Green, Blue, Saturation, and Luma buttons to activate their corresponding curves. Manipulate the shape of each curve over the luma range that you want to affect. The value of the parameter that corresponds with the curve changes relative to the height of the point on the curve in the curve editing area.

Each curve is a hue gradient and as the shape of the curve changes, the colors along the curve's gradient change to reflect the result. For example: