1. An image generating apparatus for generating a smoothing-processed image from a multi-valued image picked up by an image pickup device, the apparatus comprising: an image reducing device for generating a reduced image by reducing the multi-valued image picked up by the image pickup device; a smoothing device for executing smoothing processing on the reduced image; an edge image generating device for generating an edge image based upon the reduced image; an edge angle information generating device for generating edge angle information concerning edge angles in pixel units from the generated edge image; a rate calculating device for calculating a synthesizing rate of the multi-valued image and the smoothed reduced image in pixel units of the reduced image based upon the generated edge angle information; an image enlarging device for generating an enlarged image by enlarging the smoothed reduced image to an identical scale as the multi-valued image; a rate converting device for converting the synthesizing rate calculated in pixel units of the reduced image into a synthesizing rate in pixel units of the enlarged image; and an image synthesizing device for synthesizing the multi-valued image and the enlarged image based upon the converted synthesizing rate.