| 摘要 |
Halftone dots are formed by employing a halftone-dot forming template having a plurality of divided minute grid elements with respective predetermined threshold levels assigned thereto, and comparing the signal level of an image signal with the threshold level of each of the grid elements. There is provided a composite halftone-dot forming template composed of two, Fig. 3, or more (n) selectable halftone-dot forming templates arranged side by side. The threshold pattern templates of the composite halftone-dot forming template are selected from a template memory according to the characteristics of a photoelectric transducer scanning on original, the screen ruling, the screen angle, and other factors. The threshold levels of the respective grid elements of the composite halftone-dot forming template are of different values from each other, those grid elements the difference between which corresponds to one threshold gradation belonging to different ones, respectively, of the halftone-dot forming templates. <IMAGE>
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