Figure 12-17

Select the Gamma charts to see how the graphs alter the image.

Gamma is a way of thinking about the exposure of an image to light. On the graphs, the horizontal axis represents light input (hitting the sensor) and the vertical axis is the light output (based on the signal sent out by the sensor). Push the curve one way and you'll increase contrast in the mid-range grays (middle graph). Push the curve the other way and you'll reduce the contrast (bottom graph).