Posterizing

Posterizing is a digital image processing technique that reduces the number of distinct colors in an image. This results in a flattened, simplified appearance, often resembling a poster print where smooth gradations of color are replaced by larger areas of solid color. The process involves quantizing the color values of each pixel in an image. Instead of a continuous range of colors, posterizing assigns each pixel to one of a limited set of pre-defined colors. This reduction in color depth can create a stylized and graphic look.

The effect is achieved by reducing the number of bits used to represent each color channel (red, green, blue). For example, an 8-bit color depth for each channel allows for 256 possible values per channel, resulting in millions of colors. Posterizing might reduce this to, say, 4 bits per channel, leaving only 16 possible values per channel and drastically limiting the total number of colors. This limitation leads to the formation of distinct color bands or areas.

Posterizing is often used for artistic effect, to create a retro or graphic novel aesthetic. It can also be employed to simplify complex images for specific applications or to reduce file size, although this is less common with modern compression techniques. The degree of posterization can typically be adjusted, allowing users to control the number of distinct color levels in the final image.