How to adjust contrast curves to adjust the contrast of RGB, Grayscale, and CMYK independently.
Contrast curve adjustment
In Color Factory Settings, expand the relevant channel and select Color & Contrast.
Open the Contrast Curves Before CM tab.
The following dialog appears.
On these tabs you can manually adjust contrast curves for Grayscale, RGB, and CMYK images.
Note: There are separate tabs for the application of curves before and after the application of Color Management.
When you select a curve option and select Edit Curve, you can choose the color channel to adjust and drag the curve as you wish. You can also load or save Photoshop curves (*.amp, *.acv) directly from the curve edit window. Note that RGB curves have an absolute black value in the lower-left corner of the diagram, while CMYK and grayscale images have an absolute black value in the upper-right corner (similar to Photoshop).
When processing, the individual color curves are applied first, then the master curve.