Glossary A–ZLetter C
Colour depth
Colour depth states how many bits per primary colour a display or image file uses to distinguish brightness levels.
At 8 bits there are 256 levels per colour, around 16.7 million colours in total. At 10 bits there are 1024 levels per colour.
Colour depth becomes visible mainly in soft gradients, such as a sky, a coloured background or a shadow. If it is insufficient, the gradient breaks into visible steps or bands. In screen networks, 8 bits is sufficient for most content; greater colour depth matters for HDR content and high-quality brand presentations.
Operators should know that the whole chain counts: file, player, connection and display. A 10-bit display shows no finer steps if the video is encoded with only 8 bits. Some displays also reach higher levels by rapidly alternating between neighbouring colours. Steps in a gradient are also often caused by heavy video compression rather than by the display.