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Digital halftoning with minimum visual modulation patterns

  • US 4,920,501 A
  • Filed: 10/19/1988
  • Issued: 04/24/1990
  • Est. Priority Date: 10/19/1988
  • Status: Expired due to Term
First Claim
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1. A method of generating a halftone image with an electronic digital computer, comprising the steps of:

  • a. providing a set of minimum visual noise L×

    M bit binery patterns by employing a stochastic combinatorial minimization technique and a human visual modulation transfer function (MTF) weighting function to generate a halftone bit pattern for each density level of the multi-level digital image signal, each pattern corresponding to a possible density level of a multiple level digital image signal;

    b. providing a digital image having pixel values representing density levels; and

    c. for each pixel value of the digital image signal, modularly selecting a portion of the binary bit pattern from the corresponding pattern of the set by addressing the bit pattern with lower significant bits of an x,y pixel address associated with each pixel, and employing the selected portion to form the halftone image.

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