Editing & Post-Production
Alpha channel
Also called: alpha, transparency channel
Colour takes three channels: red, green and blue. Alpha is the fourth, and it records how opaque each pixel is, from fully see-through to fully solid. It is why a PNG logo sits over footage with no white box behind it. Exporting is where creators get caught. H.264 in an MP4 cannot carry an alpha channel, so a graphic exported that way arrives in the edit inside a black rectangle. Overlays need ProRes 4444, an image sequence, or another format your editor lists as alpha-capable.