alpha channel

noun

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

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Meanings

nounalpha channel (plural alpha channels)

plural alpha channels

  1. computer graphicsA numerical value specifying a level of translucency to be applied to a colour.

Origin

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.

Full word history & related roots →

Translations

Finnish alfakanava
  • alfakanavanumeric value
Portuguese canal alfa
  • canal alfanumeric value
Cite this entry
APA

alpha channel. (n.d.). In WatkinsX Dictionary. Retrieved November 4, 2026, from https://dictionary.watkinsx.com/word/alpha%20channel

MLA

“alpha channel.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/alpha%20channel. Accessed November 4, 2026.

Chicago

WatkinsX Dictionary, s.v. “alpha channel,” accessed November 4, 2026, https://dictionary.watkinsx.com/word/alpha%20channel.

Source: alpha channel on Wiktionary, CC BY-SA 4.0.