Posterization
From The Glossary of Digital Photography
An image that has no continuous tones but rather a series of individual tones separated by distinct lines. Posterizing is often used as a creative technique; filters are available in photo-manipulation programs such as Photoshop to facilitate this. Posterization can be caused by over-manipulating a digital image, especially when lower bit-value images such as 8-bit (rather than 16-bit) are heavily manipulated. Unwanted posterization is often called banding. See also banding
