Use Alpha Levels to convert completely opaque or completely transparent areas of a matte to be semitransparent, or to convert semitransparent areas to be completely opaque or completely transparent. Because transparency is based on the monochrome alpha channel, the controls for this effect refer to complete transparency as black and complete opacity as white. This effect is very similar to the Levels effect, which performs the same operations on color channels instead of the alpha channel.

• Use Output Black Level of 0 and Input Black Level greater than 0 to convert a range of semitransparent areas to be completely transparent.

• Use Output White Level of 1.0 and Input White Level less than 1.0 to convert a range of semitransparent areas to be completely opaque.

• Use Output Black Level greater than 0 to convert a range of completely transparent areas to be semitransparent.

• Use Output White Level less than 1.0 to convert a range of completely opaque areas to be semitransparent.

This effect works with 8-bpc and 16-bpc color.

Input Black Level

Alpha channel values at this level or lower are mapped to the Output Black Level (maximum transparency).

Input White Level

Alpha channel values at this level or higher are mapped to the Output White Level (maximum opacity).

Gamma

Determines the distribution of intermediate (gray, semitransparent) values. A Gamma value of 1 produces a linear distribution of gray values. Gamma less than 1 biases the distribution toward darker gray values (more transparency). Gamma greater than 1 biases the distribution toward lighter gray values (less transparency).