JPS6423681A - Image input device - Google Patents

Abstract

PURPOSE:To generate a density difference even when a simple binary image and a half tone image are switched by independently situating some elements respectively for deciding the level of a binalization and using a half tone circuit, for instance for the simple binary image. CONSTITUTION:An operating amplifier 124 (active element) is disposed in a current/voltage converting circuit 111 for forming a comparing level for deciding the black and white between the simple binary image such as a character and the half tone image such as a photograph to independently change the comparing level, a density level and correct a shading at the time of the half tone image. The change of the comparing level of the character and the photograph is shared by a matrix resistance circuit 109 for changing the comparing level in each of the photograph, thereby, the pattern of the matrix resistance circuit 109 is shared in case of the character. Thereby, an offset part can be controlled according to an external simple input method (for instance, a dip switch) and the density change can be simply eliminated by switching the character and the photograph.