Colour banding

Inaccuracy in computer graphics

An illustration of colour banding. Only 3 bits are used for the red channel in the left two images, 8 bits in the right image.

Colour banding is a subtle form of posterization in digital images, caused by the colour of each pixel being rounded to the nearest of the digital colour levels. While posterization is often done for artistic effect, colour banding is an undesired artifact. In 24-bit colour modes, 8 bits per channel is usually considered sufficient to render images in Rec. 709 or sRGB. However the eye can see the difference between the colour levels, especially when there is a sharp border between two large areas of adjacent colour levels. This will happen with gradual gradients (like sunsets, dawns or clear blue skies), and also when blurring an image a large amount.

Colour banding is more noticeable with fewer bits per pixel (BPP) at 16–256 colours (4–8 BPP), where there are fewer shades with a larger difference between them.

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

Because the banding comes from limitations in the presentation of the image, blurring the image does not fix this.

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Dynamic range 24 vs 36 bit

Colour topics

Colour science

Colour physics	Electromagnetic spectrum Light Rainbow Visible Spectral colours Chromophore Structural colouration Animal colouration Colour of chemicals Water Spectral power distribution Colorimetry
Colour perception	Chromesthesia Sonochromatism Colour blindness Achromatopsia Dichromacy Colour calibration Colour constancy Colour task Colour code Colour temperature Colour vision test Evolution of colour vision Impossible colours Metamerism Opponent process Afterimage Unique hues Tetrachromacy The dress
Colour psychology	Colour symbolism Colour preferences Lüscher colour test Kruithof curve Political colour National colours Chromophobia Chromotherapy
Colour reproduction	Colour photography Colour balance Colour cast Digital image processing Colour management Colour printing Multi-primary colour display Quattron Colour model additive RGB subtractive CMYK Colour space Colour mapping

Colour
philosophy

Colour scheme	Colour tool Monochromatic colours black-and-white Complementary colours Analogous colours Achromatic colours (Neutral) Polychromatic colours Light-on-dark Web colours Tinctures in heraldry
Colour theory	Colour mixing Primary colour Secondary colour Chromaticity Colour solid Colour wheel Colour triangle Colour analysis (fashion) Colour realism (art style) On Vision and Colours (Schopenhauer) Theory of Colours (Goethe)

Colour terms

Basic terms	Blue Green Red Yellow Pink Purple Orange Black Grey White Brown
Cultural differences	Linguistic relativity and the colour naming debate Blue–green distinction in language Colour history Blue in culture Colour in Chinese culture Traditional colours of Japan Human skin colour
Colour dimensions	Hue Dichromatism Colourfulness Pastel colours Luminance Lightness Darkness Brightness Iridescence Fluorescence Grayscale Tint, shade and tone

Colour
organisations

Names

Lists	List of colours: A–F List of colours: G–M List of colours: N–Z List of colours (compact) List of colours by shade List of colour palettes List of colour spaces List of Crayola crayon colours history Colour chart List of RAL colours List of web colours
Shades of:	Red Orange Yellow Green Cyan Blue Violet Purple Magenta Pink Brown White Gray Black