Image processing apparatus, image processing method, printing apparatus, and storage medium

An image processing method for processing image data, the image processing method comprising:

• obtaining image data;
• determining a plurality of unit mask patterns to be used in a multi-pass printing;
• generating print data for applying an ink and a reaction liquid that prompts thickening of the ink to a print medium corresponding to each pass of the multi-pass printing by processing the image data obtained in the obtaining step using the plurality of the unit mask patterns determined in the determining;
• and
• performing the multi-pass printing based on the print data generated in the generating, in which (1) a printing scan of a printing unit while ejecting the ink and the reaction liquid and (2) a conveyance operation of the print medium in a direction crossing a direction of the printing scan are executed alternately, to complete an image in a unit area of the print medium by a plurality of passes of the printing unit,
• wherein, in the determining, appropriate unit mask patterns are determined from the plurality of unit mask patterns such that the ink is applied to the unit area only in a pass of which an elapsed time after application of the reaction liquid to the print medium is equal to or longer than a first time and shorter than a second time, in the multi-pass printing,
• wherein the first time is from a timing where the reaction liquid is applied to the print medium up to a timing where adjacent droplets of the applied reaction liquid come into contact with each other and coalesce to form a reaction liquid film, and
• wherein the second time is from the timing where the reaction liquid is applied to the print medium up to a timing where the formed reaction liquid film is dissolved.

A non-transitory computer-readable storage medium storing a program for causing a computer to function as an image processing apparatus, the image processing apparatus comprising:

• a printing unit configured to eject an ink and a reaction liquid that prompts thickening of the ink;
• a conveyance unit configured to convey a print medium, wherein a multi-pass printing is performed in which (1) a printing scan of the printing unit while ejecting the ink and the reaction liquid and (2) a conveyance operation of the conveyance unit conveying the print medium in a direction crossing a direction of the printing scan are executed alternately, to complete an image in a unit area of the print medium by a plurality of passes of the printing unit;
• an obtainment unit configured to obtain image data;
• a holding unit configured to hold a plurality of unit mask patterns usable in the printing scan;
• and
• a generation unit configured to process the image data to generate print data for applying the ink and the reaction liquid to the print medium such that the print data corresponds to respective passes of the multi-pass printing,
• wherein the generation unit generates the print data for the ink by determining appropriate mask patterns from the plurality of unit mask patterns such that the ink is applied to the unit area only in a pass of which an elapsed time after application of the reaction liquid to the print medium is equal to or longer than a first time and shorter than a second time,
• wherein the first time is from a timing where the reaction liquid is applied to the print medium up to a timing where adjacent droplets of the applied reaction liquid come into contact with each other and coalesce to form a reaction liquid film, and
• wherein the second time is from the timing where the reaction liquid is applied to the print medium up to a timing where the formed reaction liquid film is dissolved.