Extracting a Key Using the Luma Keyer

 
 
 

The Luma Keyer computes the luminance of the image and removes pixels based on a threshold value, affecting the alpha channel. The softness value can be added to set some fall-off for the key. When the softness is 0, only the pixels that fall within the tolerance range are keyed out. The luminance keyer can either output a matte or a pixel selection.

The Luma Keyer UI has four controls.

Use: To:
Channel Select the luma or the color channel luminance that will be used to pull a key.
Key Set the range of pixels to key based on the threshold range.
Threshold Set the range of the pixels to key. Increasing the threshold removes less prevalent pixels from the composition.
Softness Soften the edge of the key.
NoteKey, Threshold, and Softness are animatable attributes—see Marking Attributes for Keyframing.