Introduction Hello. I have recently been spending a lot of time dithering. In image processing, dithering is the act of applying intentional perturbations or noise in order to compensate for the information lost during colour reduction, also known as quantisation. In particular, I've become very interested in a specific type of dithering and its application…

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A deep technical exploration of ordered dithering techniques for arbitrary and irregular colour palettes. Covers the fundamentals of ordered vs error-diffusion dithering, then progressively introduces advanced algorithms: N-closest (inverse distance weighting), N-convex, Thomas Knoll's pattern dithering, barycentric coordinate interpolation, Delaunay triangulation-based tetrahedral dithering, and natural neighbour interpolation. Also discusses threshold matrices (Bayer, halftone, blue noise) and noise functions. The author introduces Tetrapal, an open-source C library implementing Delaunay triangulation for palette dithering with barycentric and natural neighbour interpolation.

Ordered Dithering with Arbitrary or Irregular Colour Palettes

Appendix III: Threshold Matrices and Noise Functions