This gamma correction operator gets its input from a radial gradient source. This is modelled with the left orange connection. The mesh sink on the right is connected with an second orange connection to get the gamma operator values. The gamma parameter is set manually to 1.5 by the user. But this gamma parameter is additionally influenced from a linear gradient source. This source is connected with an blue connection to the 'ga' control input of the gamma operator. All control inputs are multiplied with the manually adjusted parameters. In this example the gamma parameter ranges form 0.0 on the left, to 1.5 on the right.

To establish a control connection drag the left mouse button LMB from the source node exactly to the control area of the sink node.