ELECTRONIC HALFTONE SCREENING WITH HALFTONE CELLS APPROXIMATING A PARALLELOGRAM

摘要

ELECTRONIC HALFTONE SCREENING WITHHALFTONE CELLS APPROXIMATING A PARALLELOGRAMABSTRACT OF THE DISCLOSUREAn electronic signal representing the density ofpixels in a scanned line in an original image and containingpixels in whole number multiples of a single line of halftonescreen partial dot values plus a predetermined extensionparameter is electronically halftoned by comparing thepictorial signal with the single line of halftone screenpartial dot values to form an electronic halftone image.An electronic screen function represented by the singleline of halftone screen values, produces automatically arotated halftone screen at a predetermined angle to theoriginal electronic image when the number of pixels inthe input, scanned line of the original document is setequal to a whole number multiple of the number of partial-dot values plus a predetermined extension parameter. Underthese conditions, the scanned input is automatically half-tone screened electronically into halftone cells approxi-mating a parallelogram and having said predetermined angle.The single line of partial-dot values need only be cir-cularly buffered through a comparator. No electronicindexing or shifting of partial-dot values is required.