Abstract: There has been an inefficient respect for printing control in a color printer in which only nozzle columns for black ink are high resolution. For a color printer 17b equipped with a plurality of nozzles arranged zigzag so that dark color ink droplets and light color ink droplets can be squirted onto one pixel at high resolution, resolution reduction to combine adjoining two lines into one line is performed (in step S400) and dark-light color separation is performed (in step S500), and subsequently nozzles for dark color ink and nozzles for light color ink squirt ink droplets for one pixel of pixels of two lines, thereby handling pixels for two lines as one pixel, and hence it is possible to realize high-speed printing mode with reduced scanning number to squirt ink droplets for all pixels of high resolution.