Channel > Alpha Levels effect (Pro only)

The Alpha Levels effect increases or decreases the transparency of a matte. Use Alpha Levels to adjust pure black or pure white areas of a matte to be semitransparent, or to adjust grays (semitransparent areas) to be pure black and white. Alpha values are converted using Input limits, Output limits, and the Gamma value.


Original (left) and effect applied to arches layer with Input Black Level set to 144 and Output White Level set to 90 (center), and with Output Black Level set to about 120 and Output White Level set to 0 (right)

Adjust the following controls for the Alpha Levels effect:

Input limits, Output limits

Specify where transparency begins and ends.

Gamma

Affects the range of gray values that are converted. A Gamma value of 1 produces a gradual (linear) distribution of gray values. A Gamma value of less than 1 creates darker gray values and more transparency. A gamma value of greater than 1 creates lighter gray values and less transparency.

To convert grays in the matte to pure black or white:

1. Set the Input Black Level to a gray value. Alpha values at this level or lower become fully transparent (black).
2. Set the Input White Level to a gray value. Alpha values at this level or higher become fully opaque (white).
3. Leave the Output Black Level set to 0 and the Output White Level set to 255.
4. If necessary, adjust the Gamma value to increase or decrease transparency.

To convert pure black and white in the matte into gray areas:

1. Leave the Input Black Level at 0 and the Input White Level at 255.
2. Set the Output Black Level slider to a gray value. Alpha values below this value rise to this value.
3. Set the Output White Level to a gray value. Alpha values above this value are lowered to this value.