Editing Posterization (section)

==Cause==
The effect may be created deliberately, or happen accidentally. For artistic effect, most [[image editing]] programs provide a posterization feature, or photographic processes may be used.

Unwanted posterization, also known as [[color banding|banding]], may occur when the [[color depth]], sometimes called bit depth, is insufficient to accurately sample a continuous gradation of color tone. As a result, a continuous gradient appears as a series of discrete steps or bands of color — hence the name. When discussing [[fixed pixel display]]s, such as LCD and plasma televisions, this effect is referred to as false contouring.<ref>{{Cite web |url=http://www.cnet.com/4520-7874_1-5107912-7.html#falsecontouring |title=HDTV World Glossary |access-date=2007-06-06 |date=2007 |publisher=CNET Networks}}</ref> Additionally, [[Compression artifact|compression]] in image formats such as [[JPEG]] can also result in posterization when a smooth gradient of colour or luminosity is compressed into discrete quantized blocks with stepped gradients. The result may be compounded further by an [[optical illusion]], called the [[Mach bands|Mach band illusion]], in which each band appears to have an intensity gradient in the direction opposing the overall gradient. This problem may be resolved, in part, with [[Dither#Digital photography and image processing|dithering]].