Alfakanalit

Alfakanalit is the term used in some languages for the alpha channel, a component of digital images and video that encodes per-pixel transparency. It accompanies color channels (for example red, green, and blue in RGBA color models) and controls how a pixel blends with its surroundings during compositing.

Each pixel's alpha value represents its opacity, typically ranging from fully transparent to fully opaque. In 8-bit systems, alpha is usually 0–255; in 16-bit or floating-point pipelines it may be 0.0–1.0. During image compositing, the final color is computed by blending foreground and background pixels according to alpha: resulting_color = foreground_color * alpha + background_color * (1 - alpha).

Alfakanalit is stored separately in memory alongside color channels in many image formats and can be premultiplied, where color channels are already multiplied by alpha to optimize blending and reduce edge artifacts. Formats that commonly support alpha include PNG, WebP, and TIFF; some video codecs and container formats also carry alpha information. JPEG does not standardly include an alpha channel.

Usage spans graphic design, digital photography, game development, and video production, where transparency and translucency are essential for layering, masking, and anti-aliased edges. The concept also underpins alpha compositing in compositors and rendering engines.

See also: alpha channel; RGBA; premultiplied alpha; PNG; compositing.