JPS644348A - Modulator - Google Patents

Abstract

PURPOSE:To eliminate the adverse influence of fluctuation in quantity of light outputted from a laser without using a light modulator, by a method wherein a gamma is corrected by a gamma correcting table so that a relation between input image data and output image can establish a required total gamma per light quantity data according to total characteristics of the characteristics of the light modulator and the photosensitive characteristics of a photosensitive body. CONSTITUTION:One output beam from a beam splitter 6 is added to a light modulator 3; the other output beam is added to a light detector 7. An output signal from the light detector a7 is added to an A/D converter 8 to be converted to digital light quantity data, thereafter being added to a gamma correcting table 2. In the table 2 a plurality of data are stored, thereby conducting gamma correction so that a relation between input image data and output image data can establish a required total gamma by every light quantity data added from the converter 8. The data which were addressed by the aforesaid light quantity data and input image data and outputted from the table 2 are added to a D/A converter 9 and converted to an analog modulation image signal, thereafter being added to the light modulator 3 to drive the light modulator 3.