Glossary A–ZLetter A
Alpha channel (transparency)
The alpha channel is additional information in an image or video file that defines, for each pixel, how transparent it is.
Alongside the three colour channels red, green and blue, it states whether a pixel is opaque, partly transparent or completely invisible. This allows logos, shadows and soft edges to sit cleanly over a background.
On screens the alpha channel is mainly needed for layers: a logo sits in the corner over a video, a price badge over a product photo, a lower third over a film. Without transparency, a white or black rectangle appears around such elements. Among image formats, PNG and WebP carry an alpha channel, whereas JPEG does not.
Operators should be aware that transparency in video rarely works reliably. Only a few video formats can store an alpha channel, and many players do not render it. It is safer to create moving backgrounds as video and place transparent elements as images in a separate zone on top. Before use, the file should be checked on the target device and not only on a desktop computer.