Alpha Channel

An alpha channel is a fourth channel accompanying the red, green, and blue color channels that stores how opaque or transparent each pixel is. White alpha means fully opaque, black means fully transparent, and gray gives partial transparency for soft or anti-aliased edges. It is what lets graphics, logos, and rendered elements sit over other footage without a colored background. Editors rely on alpha channels when importing titles, lower thirds, or VFX renders that must composite cleanly. Codecs that carry alpha include ProRes 4444 and image sequences like PNG; many delivery codecs discard it, so transparency must be preserved through the right format or premultiplied/straight handling. Understanding alpha (and premultiplication, which blends edge pixels against a background color) prevents the dark or bright fringes that plague poorly exported graphics.