Adobe Premiere Pro basics|
Premiere Pro CS6 Techniques: 52 Color SIX: Output Levels
In this tutorial, Andrew Devis explains the level sliders in the 'Fast Color Corrector,' which help us to set up the contrast of a shot as well as change the brightness of a shot. This way of dealing with brightness and contrast is significantly better than using the 'Brightness & Contrast,' effect which tends to crush your luminance ranges and so degrade your shot. Andrew explains both the input and output sliders and show what a difference they can make to a poorly lit shot.
Tutorial, Video Tutorial