By smoothing a full-color image, staircasing of characters even in a gradation image is removed. An area to be smoothed is detected from image data having a plurality of color components, and image data included in the detected area is smoothed in units of color components.Image data which places an importance on resolution is smoothed by increasing the resolution to reproduce smooth characters and figures. Image data which places an importance on gradation characteristic is output without increasing the resolution, thus attaining high-gradation recording. A character or figure is detected from bitmap image data input from external equipment, and is smoothed. In correspondence with the density of the smoothed image data, the pulse width is switched, thereby changing the resolution of image data.