JPS5640977A - Picture processing method - Google Patents

Abstract

PURPOSE:To ensure a reproduction of a high-qnality picture, by setting the aperture size larger enough than the picture element pitch and then expressing the intermediate gradation with a partial overlap secured for the output picture element in case a plotting is carried out based on each binary-coded picture element information. CONSTITUTION:The aperture size of the picture element which is to be plotted based on each binary-coded picture element information is set larger enough than the pitch of the picture element. Then the plotting is carried out with a partial overlap secured for the output picture element and in the same pitch. In such way, the difference of the concentration becomes inconspicuous substantially for the output picture element in case the picture including the intermediate gradation is expressed by the picture element of the white or black level. Thus a picture including the smooth intermediate gradation can be obtained. In the plotter main body, a substance (glass blocks G, B) is provided right after the aperture A to give a change to the refractive index of the light. As a result, the focal point of the beam can be shifted to the photoreceptor PC, thus increasing the aperture size for the picture element to be plotted.