The Color Key texture node is used to key out a specified color in a connected texture map (figure 1).
Figure 1: The Color Key node used to key out the red color on a connected texture map
Input Image - Image to be keyed.
Key Color - The color to be keyed.
Mask - Garbage matte should be connected here.
Fill Color - The color to replace the keyed area.
Low/High Cutoff - The low and high cutoff for the color difference.
Computation GammaThe function or attribute used to code or decode luminance for common displays. The computer graphics industry has set a standard gamma setting of 2.2 making it the most common default for 3D modelling and rendering applications. - Adjusts the color range midtones before computing the difference.
Projection - Specifies the projection type to be used for this texture.
U Cutoff Low/High - Specifies the low and high edge of simple 2D cutoff in the U direction.
V Cutoff Low/High - Specifies the low and high edge of simple 2D cutoff in the V direction.