Place this effect on a clip that contains an alpha channel, such as a Chroma keyed video clip, or a text element. Adjust the Grow control to increase or shrink the size of the alpha mask. Adjust the Blur control to blur the alpha mask. Finally, set how the alpha channel is interpreted by using the Invert or Premultiply options.
- Grow sets the size of the alpha mask. Turn up Grow to increase the size of the alpha mask. Turn down Grow to decrease the size of the alpha mask.
- Blur sets how sharp the alpha mask is. With Blur at 0, the mask will be perfectly sharp and opaque. As you increase Blur, the mask gets softer and you can begin to see the background through it.
- Enable the Invert option to invert your alpha mask. Any areas that were previously transparent will become opaque, and any opaque areas will become transparent.
- Enable the Premultiply option to blend the transparent edges of your alpha channel with the video background. Depending on your image, this can help your keyed image to blend better with the background. (Please note: in most cases this will provide only a subtle difference.)
- Enable the Test Mask option to see the image as a black and white mask. This makes it much easier to calibrate the affected area.