Adjusting the Tone Correction
Adjusting the tone levels lets you change the pixel brightness in the midtones, highlights, and shadows of an image without dramatically changing it. This modifies the contrast in image tones so they reproduce with greater detail.
To adjust the tone correction, click the Tone Correction icon, , from the advanced screen when the preview window displays your image. You see the following dialog box:
Tone curve
You can adjust the tone values by dragging points on the tone curve. You see the effect of your new settings in the preview window.
Using the Channels radio buttons, select the color(s) you want to modify the tone correction for. You can select all colors (RGB) or only red, green, or blue.