The present invention efficiently optimizes a non-ejection correction parameter for each nozzle. The non-ejection correction parameter for each nozzle is optimized by repeatedly executing the operations of generating test chart data based on a non-ejection correction parameter for each of a plurality of nozzles provided on an ink-jet head; acquiring read data of a test chart recorded on a recording medium by ejecting ink from the plurality of nozzles based on the test chart data while relatively moving the ink-jet head and the recording medium; evaluating a correction intensity of the non-ejection correction parameter for each of the nozzles based on the acquired read data; and updating the non-ejection correction parameter for each of the nozzles based on a single variable root-finding algorithm using iteration method from the evaluated correction intensity.