This effect works with 8-bpc color.

Use 2nd Layer

Retrieve values from Source Layer, which can be any layer in the composition.

From

Which values to use as input; the first several items in the menu are actually multichannel combinations of input and output options, so they don’t require you to set a To value.

• Saturation Multiplied uses the saturation value multiplied by the lightness value, where lightness is the minimum distance to black or white. For example, a dark or light blue pixel has a lower value than a bright or pure blue pixel. This option represents the most common view of a pixel’s saturation value.

• Min RGB uses the lowest value among the red, green, and blue channel values.

• Max RGB uses the highest value among the red, green, and blue channel values.

To

The channels to which to apply the values. Choose Red Only, Green Only, and Blue Only to apply the value to one channel only and set the other color channels to zero. Choose Alpha Only to apply the value to the alpha channel and set the color channels to 1.0. When you select Hue Only, the applied hue value is combined with 50% lightness and 100% saturation. When you select Lightness Only, the applied lightness value is combined with 0% saturation, which then gives the hue no influence. When you select Saturation Only, the applied saturation values are combined with 0% hue and 50% lightness.

Invert

Inverts (subtracts from 1.0) the output channel values.

Solid Alpha

Makes the alpha channel value 1.0 (complete opacity) throughout the layer.