A digital halftoning technique for the efficient transformation of gray-scale images into bilevel ones, based on the progressive generation of the bilevel image pixels in a parallel way, is presented. An image distortion criterion, in which the gray-tone image is approximated by a filtered version of the halftoned image, is used for this purpose. A combined scheme is also derived in which continuous-tone images are progressively coded and transmitted in bilevel form and can be reconstructed in gray-scale form.
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