alpha channel

English

Etymology

Coined by Alvy Ray Smith and Ed Catmull in the 1970s. Smith writes: "We called it that because of the classic linear interpolation formula $\alpha A+(1-\alpha )B$ that uses the Greek letter $\alpha$ (alpha) to control the amount of interpolation between, in this case, two images A and B". That is, when compositing image A atop image B, the value of $\alpha$ in the formula is A's alpha channel.

Noun

alpha channel (plural alpha channels)

1. (computer graphics) A numerical value specifying a level of translucency to be applied to a colour.

Translations

numeric value

• Finnish: alfakanava
• Portuguese: canal alfa m