Abstract: In a digital image forming apparatus with use of electrophotographic process, an electrostatic latent image is formed by modulating the intensity of laser beam according to image data to expose a photoconductor in the raster scan to form an electrostatic latent image. A scan line is divided into groups of consecutive dots, and the exposure of the photoconductor with the beam is allowed only for a predetermined light-emitting time within the time needed to scan a predetermined period of consecutive dots in the scan line direction. Thus, the exposure is stopped periodically and the smoothness of a reproduced image is improved.