page_title: Dither
section_title: Digital photography and image processing
hierarchical_section_title: Dither / Digital photography and image processing
context_page_description: Dither is an intentionally applied form of noise used to randomize quantization error, preventing large-scale patterns such as color banding in images. Dither is routinely used in processing of both digital audio and video data, and is often one of the last stages of mastering audio to a CD.
  A common use of dither is converting a greyscale image to black and white, such that the density of black dots in the new image approximates the average grey level in the original.
context_section_description: Dithering is used in computer graphics to create the illusion of color depth in images on systems with a limited color palette. In a dithered image, colors that are not available in the palette are approximated by a diffusion of colored pixels from within the available palette. The human eye perceives the diffusion as a mixture of the colors within it (see color vision).  Dithered images, particularly those using palettes with relatively few colors, can often be distinguished by a characteristic graininess or speckled appearance.
  Dithering introduces noise or a pattern into an image, and often the patterning is visible. In these circumstances, it has been shown that dither generated from blue noise is the least unsightly and distracting. The error diffusion techniques were some of the first methods to generate blue-noise dithering patterns. However, other techniques such as ordered dithering can also generate blue-noise dithering without the tendency to degenerate into areas with artifacts.
caption: An illustration of dithering. Red and blue are the only colors used but, as the red and blue squares are made smaller, the patch appears purple.