Posterization

It can now be done photographically or with digital image processing, and may be deliberate or an unintended artifact of color quantization.

For artistic effect, most image editing programs provide a posterization feature, or photographic processes may be used.

As a result, a continuous gradient appears as a series of discrete steps or bands of color — hence the name.

When discussing fixed pixel displays, such as LCD and plasma televisions, this effect is referred to as false contouring.

Typically, posterization is used for tracing contour lines and vectorizing photo-realistic images.

Unlike a pulldown, the unused frames are simply discarded, and it is intended to be apparent (longer than the persistence of vision that video and motion pictures normally depend on).

Example of a photograph in JPEG format (24-bit color or 16.7 million colors) before posterization, contrasting the result of saving to GIF format ( 256 colors ). Posterization occurs across the image, but is most obvious in areas of subtle variation in tone.
Posterized photo of a hibiscus
Posterized photo