Blue Noise

Blue noise's (a.k.a. azure noise) power density increases 3 dB per octave with increasing frequency (density proportional to f ) over a finite frequency range. In computer graphics, the term "blue noise" is sometimes used more loosely as any noise with minimal low frequency components and no concentrated spikes in energy. This can be good noise for dithering;retinal cells are arranged in a blue-noise-like pattern for this reason.