The visual aspects you can edit are as follows:
This slider expands or shrinks the overall range of tonal values in the image.
This slider to the right increases tonal values and expands image highlights, to the left decreases values and expands shadows.
This slider adds or removes colour in proportion to the image
Curve that describes how the middle tones of images appear. Gamma is a nonlinear function often confused with "brightness" and/or "contrast." Changing the value of the gamma affects middle tones while leaving the white and black of the image unaltered. Gamma adjustment is often used to compensate for differences between Macintosh and Windows video cards and display.
Drag the slider to change the values. The preview at the top updates in real-time.
The buttons reading from left to right are as follows: