The Fog filter creates a soft, misty atmosphere over the image and glows highlights.

Diffusion.

To select a preset, choose one from the Presets tab.

Determines the blend mode to be used to create the fog effect.

The fog is added to your image.

The fog is combined with the image using a Screen blend mode. This looks kind of like the Add blend mode, but highlights are retained.

Sets the intensity of the fog.

Sets the softness of the fog.

The Color parameter sets the color of the fog through the use of a standard color picker. The default color is white.

A matte is used to create the fog effect. Go to the Matte section of Common Node Controls to see how the Matte controls work.