Extracting a Key Based on Luminance

You can create a key using only the Luminance channel. This technique is most often used for shots filmed against a black background, or when bringing in a matte (for example a black and white logo) as a key-in source.

You can also use the Luma mode to adjust a matte that has already been rendered. Load the matte as the key-in clip then adjust it using the Key controls in Luma mode.

To create a key by setting the luminance:

1. In the Key controls, select Luma from the Keyer Mode list.

In the front clip, black is transparent, and white is opaque.

2. Adjust the tolerance to key out more of the blacks.

Increasing tolerance increases the range of pixels that will be completely transparent. Tolerance values are expressed in percentage. A value of 100 makes the front image completely transparent.

3. Set the softness. By default, softness is set to 100. Increasing softness makes the image more transparent. When softness is 0, only pixels that fall within the tolerance range are keyed out. The matte is black and white with no grays.