posterisaatio

Posterisaatio is a term originating from the field of image processing and digital art. It refers to the process of reducing the number of distinct colors used in an image. This reduction is achieved by mapping a range of similar colors to a single, representative color. The result is an image that appears to have fewer colors, often giving it a stylized, graphic, or "poster-like" quality, hence the name.

The core mechanism of posterization involves quantizing the color values. In a typical digital image, colors are represented by numerical values (e.g., Red, Green, Blue components). Posterization algorithms analyze these values and group them into a predefined, limited number of bins. All pixels whose original color falls into a specific bin are then assigned the same output color, which is usually the average or a representative color for that bin.

This technique can be used for artistic effects, such as creating a vintage look or a bold, graphic design. It can also be employed to reduce file sizes for images where color fidelity is not paramount. The degree of posterization can be controlled by adjusting the number of colors or levels the image is reduced to. More levels result in a smoother transition between colors, while fewer levels create a more pronounced, blocky effect. Many image editing software applications offer a "posterize" or "color levels" feature that allows users to easily apply this effect.