English Explanatory Dictionary

alpha channel

English dictionary entry

Meanings

noun
  1. A numerical value specifying a level of translucency to be applied to a colour.

Word forms

alpha channel alpha channels

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 αA+(1-α)B that uses the Greek letter α (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 α in the formula is A's alpha channel.

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