Method and apparatus for generating screened halftone images
First Claim
1. A method for generating screened halftone images in order to reproduce an original, which comprises an area of halftone dots with desired periodicity and tone reproducibility, subdividing said area into minute cells, setting address values (X, Y) for each minute cell, computing out the threshold value of density for each of said cells of said area as a function f (X, Y) of the relevant address values (X, Y), using the computed value for each cell as the threshold value of density for the cell, obtaining a density-related video signal of the portion of the original corresponding to each of said cells by scanning the original, and obtaining screened halftone dot signals by comparing the video signals with the signals of threshold value of density.
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Abstract
Apparatus and method for generating screened halftone images, which includes means for assuming an area of halftone dots with desired periodicity and tone reproducibility, subdividing the area into minute cells and setting address values (X, Y) for each of the minute cells, computing out a threshold value of density for each of said cells as a function f (X, Y) of the relevant address values (X, Y), and using the computed value as threshold value of density for the cell, means for obtaining a density-related video signal of the portion of the original corresponding to each of said cells by scanning the original, and means for producing halftone dot signals by comparing the video signals and the threshold value of density with each other.
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4 Claims
- 1. A method for generating screened halftone images in order to reproduce an original, which comprises an area of halftone dots with desired periodicity and tone reproducibility, subdividing said area into minute cells, setting address values (X, Y) for each minute cell, computing out the threshold value of density for each of said cells of said area as a function f (X, Y) of the relevant address values (X, Y), using the computed value for each cell as the threshold value of density for the cell, obtaining a density-related video signal of the portion of the original corresponding to each of said cells by scanning the original, and obtaining screened halftone dot signals by comparing the video signals with the signals of threshold value of density.
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3. Apparatus for generating screened halftone images, comprising means for assuming an area of halftone dots with desired periodicity and tone reproducibility, means for setting address values (X, Y) for each minute cell obtained by subdividing said area, means for computing out the threshold value of density for each of said cells of said area as a function f (X, Y) of the relevant address values (X, Y) and using the computed value as the threshold value of density for the cell, means for obtaining a density-related video signal of the portion of the original corresponding to each of said cells by scanning the original, and means for obtaining screened halftone dot signals by comparing the video signals and the signals of threshold value of density with each other.
Specification