Using Blender's Color Correction Node in Compositing
Learn to use the color correction compositing node for fine tune control
http://cgcookie.com/blender/2013/01/23/using-the-color-correction-compositing-node-in-blender/
The Color Correction node allows you to adjust the highlights, midtones, and shadows of your render to perfect the final result. However, it is much more than just adjusting a few sliders and gives you a lot of power.
This tutorial gives you a detailed explanation of each aspect of the Color Correction compositing node. Introducing Gain, Gamma, Lift, and Slope, Power, Offset color grading algorithms.
If you're new to color correction, color management, and compositing in general then I highly recommend you check out our Compositing in Blender training series.