Free public beta until December 4, 2026: every course is open, no card needed. After that, the first chapter of each course stays free and full access is a one-time $39 ($19 for up to 100 founding members chosen for helpful feedback). Your progress is kept. How the beta works

channel

One of the stacked grayscale-shaped layers that make up a multichannel image.

A channel is one grayscale-shaped layer of a multichannel image, stacked along a third axis of shape $(H, W, C)$ — three channels for RGB, but any count $C$ is possible (a satellite sensor's spectral bands, for instance).