In low-resolution processing (reduction processing) in which input image data is separated into character print data and image print data to generate print data of lower resolution than that of the input image data, if a plurality of pixels is simply reduction-processed to one pixel, color of a color image surrounding a character may change. In an image processing method, calculation for performing reduction processing so that the plurality of pixels in the input image data corresponds to one pixel in the print data is performed as follows. A ratio of using a pixel value of a character attribute pixel in the calculation is set to 0, or set smaller than a ratio of using a pixel value of an image attribute pixel. As a result, a change in the color of the color image surrounding the character can be prevented.