Atkinson dithering is an algorithm developed by Apple programmer Bill Atkinson. He is well-known for having created HyperCard and MacPaint, as well as user interface innovations for the Macintosh.
Dither is an intentionally applied form of noise used to randomize quantization error.
A common use of dither is converting a grayscale image to black and white, such that the density of black dots in the new image approximates the average gray-level in the original.
I explore the algorithm below - I'm intrigued by the organic patterns that appear when the image is scaled up. After this I'd like to try the Halftone dither.