A high quality gray scale (monochrome) image in which influences of “recorded color deviation” and “color transition” are suppressed is formed even in the case of a slightly uneven discharge amount. When a gray scale (monochrome) mode is set, in the entire range of a luminance signal, density signals corresponding to achromatic dots and small chromatic dots respectively are generated based on the luminance signal so that the density signal corresponding to the achromatic dots has a greater value than that of the density signal corresponding to the small chromatic dots. Accordingly, even a slight “recorded color deviation” that occurs when the achromatic dots are recorded can be corrected by the small chromatic dots having a hue opposite to the direction of color deviation, and a high quality gray scale image in which influences of “recorded color deviation” and “color transition” are suppressed can be formed.