dithered

Dithered is a term used in digital signal processing and computer graphics to describe a technique used to simulate greater color depth or grayscale resolution in images with a limited color palette. It involves intentionally introducing a controlled amount of noise or randomness to the image. This noise is not random in the true sense but is patterned or structured to spread out the quantization error that occurs when a continuous range of tones or colors must be represented by a smaller, discrete set of values.

The process of dithering can be understood as a way to fool the human eye into perceiving intermediate shades or tones that are not explicitly present in the original color palette. By strategically arranging pixels of available colors, dithering creates the illusion of smoother transitions and more detail, especially in areas with gradients. Without dithering, images with limited color palettes can exhibit noticeable banding or posterization, where distinct steps in tone are visible instead of a smooth progression.

Different dithering algorithms exist, each with its own method of distributing the noise. Some common methods include ordered dithering, which uses a predefined pattern, and error-diffusion dithering, which distributes the quantization error to neighboring pixels. The choice of dithering algorithm can impact the visual quality and the appearance of the resulting noise. Dithering is particularly useful when reducing the color depth of an image for display on devices with limited capabilities or for reducing file size.