What is an Alpha channel?
The alpha channel first introduced by Alvy Ray Smith in the 1970s, can store values between 0-1, signifying whether a specific pixel is transparent, opaque, or semitransparent. Though this channel is boring to look at, this information is very essential when merging footages. Alpha information can be stored either independent of RGB, referred to as straight alpha, or by multiplying it with RGB, referred to as premultiplied alpha. A value of zero in the alpha channels signifies that the RGB pixel should be completely transparent, and opaque when the value is one. The following screenshot portrays an alpha channel:
