Color Correction - Nuke 101: Professional Compositing and Visual Effects - page 154

Youcan see that gamma mainly deals with midtones. The bright areas remain un-
touched and so do the dark areas.
You should now have three different, basic, math-based color correctors in your
Node Graph that produce three very different results as shown in FIGURE 4.5 .
Figure 4.5. The results from changing Add, Multiply, and Gamma.
Your DAG should look a little like FIGURE 4.6 .
Figure 4.6. Branching three color correctors from a node.