Image processing apparatus, image processing method, and storage medium

An image processing apparatus for an image forming apparatus that performs printing on a printing medium by using a print head comprising a nozzle row in which a plurality of nozzles ejecting ink is arrayed in one direction, the image processing apparatus comprising:

• one or more processors;
• and
• one or more memories that store computer-readable instructions for causing, when executed by the one or more processors, the image processing apparatus to function as:
• a detection unit configured to detect a non-ejectable nozzle that cannot eject ink normally among nozzles configuring the nozzle row;
• an acquisition unit configured to acquire a nozzle row characteristic indicating a characteristic of each nozzle based on a scanned image of a first chart including a plurality of patches, which is output from the image forming apparatus;
• a creation unit configured to create a template indicating influence exerted by the non-ejectable nozzle based on a scanned image of a second chart including a plurality of patches, which is output from the image forming apparatus;
• and
• a generation unit configured to generate density correction information for reducing density unevenness in the printing, wherein
• the first chart and the second chart include a plurality of patches having different tones and extending in a direction of the nozzle row,
• each patch of the second chart includes at least a portion in which a dot is not formed at a position corresponding to a specific nozzle in the nozzle row,
• the generation unit:
• acquires the nozzle row characteristic including the influence of the non-ejectable nozzle by applying the template in accordance with a position of the non-ejectable nozzle detected by the detection unit to the nozzle row characteristic acquired by the acquisition unit;
• and
• generates density correction information that specifies an output tone value for implementing a target density for an input tone value for each nozzle based on the acquired nozzle row characteristic including the influence of the non-ejectable nozzle the second chart further includes a pattern for detecting the non-ejectable nozzle,
• the detection unit detects the non-ejectable nozzle by analyzing the pattern in the scanned image of the second chart that is output from the image forming apparatus, and
• the creation unit creates the template based on the non-ejectable nozzle detected by the detection unit.