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 behaves as the background. After introducing the alpha channel, the background information 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.