อัลฟ่าแชนแนล (Alpha Channel)

The alpha channel extends a color from three components (RGB) to four (RGBA), with alpha typically ranging from 0 (fully transparent) to 1 (fully opaque) or 0 to 255 in 8-bit representation. It was introduced by Alvy Ray Smith and Ed Catmull at Lucasfilm in 1977 for compositing visual effects. In web design, the alpha channel is supported across all modern CSS color functions: rgba(), hsla(), and the newer color notations with the / syntax (rgb(255 0 0 / 50%)). PNG and WebP image formats support alpha channels, while JPEG does not.