| 摘要 |
In a method of producing a digital half-tone representation of an original image, wherein the representation is constituted by an array of output cell values representing the colour content of pixels of the original image, cell values are determined for successive output cells, for which cell values have not previously been determined. An output cell value is generated with reference to an input cell value related to the colour content of a corresponding pixel in the original image, and any error values propagated from previous iterations. Where the output cell value satisfies a predetermined condition, the effective colour content of a neighbourhood of previously determined output cell values is determined by addressing a look-up table containing a single value for each neighbourhood. An error value constituted by the difference between the effective colour content and the corresponding input cell value is determined and propagated for use in subsequent iterations.
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