Image processing apparatus, image processing method, and storage medium

An image processing method for performing printing on a printing medium by using a print head including a plurality of nozzles ejecting ink, the method comprising:

• detecting a non-ejectable nozzle that cannot eject ink normally among the plurality of nozzles;
• acquiring density correction information that specifies an output tone value for implementing a target density for an input tone value for each nozzle, the density correction information is being acquired in a case where the non-ejectable nozzle is not detected after the non-ejectable nozzle recovers to an ejectable nozzle without a correction for the output tone value to complement the non-ejectable nozzle;
• changing output tone values corresponding to the detected non-ejectable nozzle and peripheral nozzles thereof among output tone values specified in the density correction information based on results of the detecting;
• exchanging pixel values of a pixel line corresponding to the non-ejectable nozzle in the printing-target image data with pixel values of a pixel line corresponding to an alternative nozzle adjacent to the non-ejectable nozzle so that a shape of an object is maintained in results of the printing based on results of detection;
• correcting a tone value of printing-target image data by using the density correction information whose output tone values have been changed;
• and
• performing the correction for the printing-target image data after pixel value exchange has been performed.

A non-transitory computer readable storage medium storing a program for causing a computer to perform an image processing method for performing printing on a printing medium by using a print head including a plurality of nozzles ejecting ink, the image processing method comprising:

• detecting a non-ejectable nozzle that cannot eject ink normally among the plurality of nozzles;
• acquiring density correction information that specifies an output tone value for implementing a target density for an input tone value for each nozzle, the density correction information is being acquired in a case where the non-ejectable nozzle is not detected after the non-ejectable nozzle recovers to an ejectable nozzle without a correction for the output tone value to complement the non-ejectable nozzle;
• changing output tone values corresponding to the detected non-ejectable nozzle and peripheral nozzles thereof among output tone values specified in the density correction information based on results of the detecting;
• exchanging pixel values of a pixel line corresponding to the non-ejectable nozzle in the printing-target image data with pixel values of a pixel line corresponding to an alternative nozzle adjacent to the non-ejectable nozzle so that a shape of an object is maintained in results of the printing based on results of detection;
• correcting a tone value of printing-target image data by using the density correction information whose output tone values have been changed;
• and
• performing the correction for the printing-target image data after pixel value exchange has been performed.