Adjust Colors

Brightness

Lightens or darkens the image.

Contrast
Changes the amount of shading between areas in the image.
Contrast and brightness usually work together because increasing the contrast can fade out detail in shadows and highlights; however, increasing the brightness can restore this detail.
Gamma
The gamma value controls the medium bright colors. Values smaller than zero brighten the image; greater values darken the image. You may want to adjust the contrast after you have corrected the gamma.
Saturation
Saturates or desaturates the colors of an image. If the colors are 100 % desaturated, the image will appear in grayscale.
Hue
You can rotate the colors of the spectrum (rainbow) in order to change the hue.
For example, if you change the red pixels to green, the green pixels will turn to blue and the yellow pixels to cyan.