Bits per Channel
The number of bits used to record each colour channel of a pixel, determining how many tonal levels are available.
Formula / rule
Levels = 2^bits
Measured in
bits
In depth
Eight bits gives 256 levels per channel, which is enough for a finished image but not for editing — stretching those levels with strong adjustments produces banding. Sixteen bits gives 65,536 levels and enormous editing headroom. The distinction matters most in smooth gradients such as skies and studio backdrops.
Examples in practice
A sky pushed two stops brighter bands visibly in 8-bit and stays perfectly smooth in 16-bit.