Noise Addition

Apply this adjustment via the Details panel using the following settings:

Intensity—controls the level of noise generated. Drag the slider to set the value.
Gaussian noise—when selected (default), produces a wider range of light and dark pixels as it uses a special curve to generate the noise. If this option is off, produces completely random noise distribution.
Color noise—when selected, the noise is distributed evenly across color channels.
Reset—reverts all adjustment settings to default.