Color ink deposition order determination method, and image forming method and apparatus

An image forming apparatus, comprising:

• an ink ejection head having a nozzle row ejecting inks of the plurality of colors;
• a scanning device by which the ink ejection head is moved relatively to a recording medium so that the ink ejection head scans a recording region on the recording medium a plurality of times;
• a density information obtaining device which obtains information on OD_β(α) concerning the ink of a first color α of the plurality of colors and OD_α(β) concerning the ink of a second color β of the plurality of colors, where OD_β(α) is a reflection density in a range of a color complementary to the second color β in a deposition sample obtained when only the ink of the first color α is deposited, and OD_α(β) is a reflection density in a range of a color complementary to the first color α in a deposition sample obtained when only the ink of the second color β is deposited;
• a deposition order determination device which determines a deposition order so that one of the inks of the first color α and the second color β which one corresponds to smaller one of OD_β(α) and OD_α(β) is first deposited and the other of the inks of the first color α and the second color β is subsequently deposited;
• and
• an ejection control device which controls operation of the ink ejection head so that the inks overlap on one another on the recording medium in accordance with the deposition order determined by the deposition order determination device.

An image forming apparatus, comprising:

• an ink ejection head having a nozzle row ejecting inks of the plurality of colors;
• a scanning device by which the ink ejection head is moved relatively to a recording medium so that the ink ejection head scans a recording region on the recording medium a plurality of times;
• a density information obtaining device which obtains information on OD_α(α→β), OD_β(α→β), OD_α(β→α), and OD_β(β→α), where OD_α(α→β) is a reflection density in a range of a color complementary to a first color α in a deposition sample obtained when an ink of a second color β is deposited on an ink of the first color α, OD_β(α→β) is a reflection density in a range of a color complementary to the second color β in the deposition sample obtained when the ink of the second color β is deposited on the ink of the first color α, OD_α(β→α) is a reflection density in the range of the color complementary to the first color α in a deposition sample obtained when the ink of the first color α is deposited on the ink of the second color β, and OD_β(β→α) is a reflection density in the range of the color complementary to the second color β in the deposition sample obtained when the ink of the first color α is deposited on the ink of the second color β;
• a deposition order determination device which determines a deposition order of the inks of the first color α and the second color β according to values of OD_α(α→β), OD_β(α→β), OD_α(β→α), and OD_β(β→α) obtained by the density information obtaining device;
• and
• an ejection control device which controls operation of the ink ejection head so that the inks overlap on one another on the recording medium in accordance with the deposition order determined by the deposition order determination device.