A tincture adjustment value used to adjust a monochrome signal to a tincture desired by a user is set, and a tincture conversion table and chromaticity line table are generated based on that tincture adjustment value and the profile of an image output apparatus. Using the generated tables, a lightness signal L* corresponding to an input monochrome signal is converted into a distance signal l on a chromaticity line, and the distance signal l is converted into a chromaticity signal (a*, b*). The lightness signal L* and chromaticity signal (a*, b*) are converted into a color signal of the image output apparatus.