JPS57155540A - Expression method for medium contrast - Google Patents

Abstract

PURPOSE:To make noise inconspicuous and to improve image quality by oscillating a density level vertically by superposing halftone information in image information and preventing the generation of the contours to be produced when the information is quantized by the smaller number of gradations effectively. CONSTITUTION:The respective parts of an original picture are scanned and the image signals corresponding to the varying densities thereof are obtained. These are quantized to image information. On the other hand, a contact screen having the density distributions wherein the density value is highest in the central part of each halftone dot and decreases gradually toward the peripheral parts is scanned and halftone signals are obtained. These signals are converted to digital signals, whereby halftone information is obtd. Image information 10 is converted to binary coded information 11. The information 11 and halftone information 12 are added to make required picture element halftone information 13, which is superposed on the information 10 and the superposed information is converted image information 14. The information 14 superposed with the halftone information in this way is fed to a recorder such as ink jet printer, by which it is recorded to the densities corresponding to those of the image information.