Multiple tonal range image processing system - has host computer converting entered gray scale image into raster image expressing multiple tonal ranges, using intermediate spot pattern determined in advance

摘要

The intermediate spot pattern is composed of pixels which can take only binary value densities with information indicating tonal ranges embedded in manner of arrangement of pixels in the spot pattern. This raster image thus logically expresses a large number of tonal ranges which cannot be actually expressed with pixels in binary value densities. A printer (20) receives this raster image from the host computer and converts the intermediate spot pattern in this raster image into an output spot pattern which can assume tertiary values or more in density, thus printing out a half-tone image actually expressing multiple tonal ranges.