PURPOSE: To realize image reproduction with high gradation reproductivity by varying the exposure energy of a beam according to the density level of the image elements of an image to be reproduced and varying the dot dimension of an image charge pattern formed on an image carrier according to a density level.

CONSTITUTION: The exposure energy is varied according to the density level of the image elements of the image so that the dot dimension of the image charge pattern formed on the image carrier varies with the developing level. Thereby, the image reproduction can be carried out with enhanced gradation reproductivity without inducing the deterioration of resolution, lowering image outputting speed shortening switching time for emitting the beam and accelerating scanning with a beam deflecting device.