High Quality Content by WIKIPEDIA articles! Posterization of an image entails conversion of a continuous gradation of tone to several regions of fewer tones, with abrupt changes from one tone to another. This was originally done with photographic processes to create posters. It can now be done photographically or with digital image processing, and may be deliberate or may be an unintended artifact of color quantization. The effect may be created deliberately, or happen accidentally. As an artistic effect, posterization may be created deliberately using most photo-editing programs or using photographic processes. A posterized photo of a hibiscus. Unwanted posterization, also known as 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.