The Contrast color adjustment layer adjusts the upper and lower bounds of your image's brightness. Add a contrast layer by clicking the Contrast icon on the Color tab of the toolbar, then adjust the selected contrast layer in the Contrast Properties panel.
Usage
Use the Contrast: slider to increase or decrease the contrast of an image. - Negative values will gray out the photograph.
- Positive values will accentuate the difference between shadows and light areas.
- A value of 0 will leave the image unchanged.