Method and apparatus for generating halftone dots

摘要

A sub scanning line counter and a main scanning position counter count absolute record-scanning position. A halftone pattern memory outputs binary image output signals for resulting halftone dots in response to comparison of halftone dot density of a halftone pattern partial position previously related with the aboslute record-scanning position determined by count values of the sub scanning line counter and the main scanning position counter with density of the image input signal at that time. A preset value calculating circuit calculates, in case of starting record-scanning from the middle of the recording screen, the count value of the sub scanning line counter corresponding to the scanning start point in advance to starting scanning, thereby to preset the calculated value in the sub scanning line counter. Thus, in case of performing halftone processing in an image scanning/recording unit such as a composing scanner, continuous halftone dots can be generated in connected portions of a plurality of duplicate recorded images obtained by separately scanning a plurality of originals.