Digital halftoning by means of green-noise masks

We introduce a novel technique for generating green-noise halftones-stochas tic dither patterns composed of homogeneously distributed pixel clusters. A lthough techniques employing error diffusion have been proposed previously, the technique here employs a dither array referred to as a green-noise mas k, which greatly reduces the computational complexity formerly associated w ith green noise. Compared with those generated with blue-noise masks, halft ones generated with green-noise masks are less susceptible to printer disto rtions. Because green noise constitutes patterns with widely varying cluste r sizes and shapes, the technique introduced here for constructing these gr een-noise masks is tunable; that is, it allows for specific printer traits, with small clusters reserved for printers with low distortion and large cl usters reserved for printers with high distortion. Given that blue noise is a limiting case of green noise, this new technique can even create blue-no ise masks. (C) 1999 Optical Society of America [S0740-3232(99)01807-4].