Color Correction - Nuke 101: Professional Compositing and Visual Effects - page 157

Multiply operation is virtually the same as changing the exposure in a camera or
increasing light. It is the most commonly used color operation.
• The Gamma control is a specific curve designed to manipulate the part of the dy-
namicrangebetween0and1(blackandwhite,remember?),withouttouching0or
1.
• Contrast is actually very similar to Multiply, but has a center control. If you place
the center point at 0 you get a Multiply node.
Using an I/O Graph to Visualize Color Operations
And I/O graph (input versus output graph) is a great way to understand color operations.
The X axis represents the color coming in, and the Y axis represents the color going out.
A perfectly diagonal line therefore represents no color correction. The graph shows what
the color operation is doing and the changes to the dynamic range.
To view an I/O graph like this, you can bring in a pre-made script I made.
1. ChooseFile>ImportScripttoloadanotherscriptfromthediskandmergeitwith
the script you have been building.
2. In the File Browser that opens, navigate to chapter04 and click IO_graph.nk to
import it into your current script.
Notice that when you imported the script (which is only four nodes) all of its
nodes were selected. This is very convenient as you can immediately move the
newly imported tree to a suitable place in your Node Graph.
3. Make sure the imported tree is not sitting on top of your existing tree. Move it
aside to somewhere suitable as in FIGURE 4.8 .
Figure 4.8. You now have two trees in your DAG.