Graphics Programs Reference
In-Depth Information
Significance of alpha in the layering
concept
The layering concept involves merging more than one piece of footage based on the
color, blending modes, or the transparency of the individual footage. In either of the
cases, one of the pieces of footages behaves as the foreground and the other be-
haves as the background. After introducing the alpha channel, the background inform-
ation perceived can be based on the alpha values. The following screenshot shows
the layering of a foreground and background using the alpha channel. This technique
is vital for merging the CG elements into live shot footage.
Following is the layering formula used in the type of layering we just discussed:
Tip
(FG * A) + (BG(1- A)) = Result
, where
FG
stands for the foreground image,
BG
stands for the background image, and
A
stands for FG Alpha.
