reducedcolor

Reducedcolor is a term used in digital imaging to describe the process or result of representing an image with a palette that contains far fewer colors than a truecolor representation. The goal is to decrease memory usage, reduce file size, or adapt images to hardware or software that supports only a limited color range, while preserving as much visual fidelity as possible.

In practice, reducedcolor involves color quantization, where the set of available colors is reduced to a chosen palette. Common techniques include uniform quantization, median-cut, octree quantization, and k-means clustering. After a palette is established, each pixel is mapped to the nearest color in that palette. Dithering algorithms, such as Floyd–Steinberg, are often applied during mapping to distribute quantization error and minimize perceptual loss, at the cost of introducing a speckled appearance.

Applications of reducedcolor include web graphics, where formats like GIF and PNG-8 use indexed color palettes, as well as embedded systems, game engines, and devices with limited display capabilities. The approach is also used in image processing pipelines to reduce bandwidth or storage requirements.

Limitations of reducedcolor include potential loss of color fidelity, banding, and artifacts if the palette is poorly chosen or dithering is inappropriate for the image content. The effectiveness of reducedcolor depends on the color space used, the chosen palette size, and the characteristics of the source image.

See also: color quantization, color depth, indexed color, GIF, PNG-8.