Printing apparatus and printing method

A printing method of performing scan printing on a print medium by using a printhead having, for each color ink, a plurality of nozzle arrays in each of which a plurality of nozzles are arrayed, the method comprising:

• setting execution selection between of a speed oriented mode and an image quality oriented mode as a mode of the scan printing;
• generating, by a print control unit, data to be transferred to the printhead for each nozzle array based on print data of one nozzle array, decimation data to decimate data corresponding to a nozzle which does not discharge ink in the print data of the one nozzle array, and information relating to an inclination of a nozzle array in a reference direction;
• reading out print data held in a first buffer memory outside the print control unit;
• and
• storing in a second buffer memory inside the print control unit print data decimated in accordance with the decimation data,
• wherein in the generating step, when executing the image quality oriented mode, the decimation data is read out from the first buffer memory to generate data to be transferred to the printhead, and
• wherein when executing the speed oriented mode, the decimation data held in advance in the second buffer memory is read out to generate data to be transferred to the printhead.