Colour banding is a problem of inaccurate colour presentation in computer graphics

Computer graphics

Computer graphics are graphics created using computers and, more generally, the representation and manipulation of image data by a computer with help from specialized software and hardware....

. While in 24 bit colour modes, 8 bits per channel should be enough to render images in the full visible spectrum

Visible spectrum

The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 750 nm. In terms of...

, in some cases there is a risk of producing abrupt changes between shades of the same colour. For instance, displaying natural gradient

Gradient

In vector calculus, the gradient of a scalar field is a vector field that points in the direction of the greatest rate of increase of the scalar field, and whose magnitude is the greatest rate of change....

s (like sunsets, dawns or clear blue skies) can show minor banding.

Colour banding is more present with relatively low bits per pixel (BPP) at 16–256 colours (4–8 BPP), where not every shade can be shown because there aren't enough bit

Bit

A bit is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states...

s to represent them.

Possible solutions include the introduction of dithering and increasing the number of bits per colour channel.