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 that 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.