For a multi-pass printing, an image of a unit area is printed by M printing scans of M print regions of first and second nozzle arrays. Each of N pieces of column data is printed by a different printing scan. Ejection data for the first nozzle array is generated using a first mask pattern and ejection data for the second nozzle array is generated using a second mask pattern different from the first mask pattern, for each of the N pieces of column data. On that basis, the first mask pattern and the second mask pattern have a complementary relationship in each of the M print regions. Further, in each of the first mask pattern and the second mask pattern, a combination of print regions, of the M print regions, for printing dots at the same position on the print medium has a mutually complementary relationship.

An inkjet printing apparatus is configured to print the image in N (N is an integer of four or more) print scanning operations of a print head for a unit region of the print medium by using N mask patterns used in the N print scanning operations. The inkjet printing apparatus includes: an obtaining unit configured to obtain defective nozzle information specifying a defective nozzle; and a correction unit configured to divide the N mask patterns into mask groups each corresponding to two or more print scanning operations and correct the mask patterns based on the defective nozzle information in each of the divided mask groups.

An object is to print a high quality image with resistance to print misalignment. To this end, the image processing apparatus generates quantized data for printing a first dot pattern and a second dot pattern in an overlapping manner. The first dot pattern and the second dot pattern are lattice patterns varying in a combination of two basis vectors. In a combined dot pattern obtained by combining the first and second dot patterns, there is a neighboring dot in which a dot in the first dot pattern and a dot in the second dot pattern are arranged at an interval smaller than a lattice spacing. The neighboring dot includes multiple neighboring dots varying in an approach direction.

A liquid discharge apparatus includes a color component divided data generation unit, a dot data generation processing unit, and a dot data segmentation processing unit. The color component divided data generation unit generates color component divided data from image data. The dot data generation processing unit applies a dot data generation mask to the color component divided data to generate dot data. The dot data segmentation processing unit applies a segmentation mask to the dot data to generate scan data. A width of the segmentation mask in a main scanning direction is different from a width of the dot data generation mask in the main scanning direction.

A method of operating a printer distributes inkjet operations from frequently used inkjets to lesser used inkjets. The redistribution of the inkjet operations helps reduce the number of inkjets exhibiting cross-process direction error so printhead maintenance operations, such as purging, occur less frequently.

According to an aspect of the embodiments, in multi-tonal image data in which each of pixels is represented by bit data of M bits (M≥2), reduction processing is performed by applying a mask pattern to the bit data to be thinned out without increasing load of calculation processing.

A first dot pattern printed according to a result of quantization performed on a multi-valued grayscale value by using a first threshold matrix and a second dot pattern printed according to a result of quantization performed on multi-valued grayscale value by using a second threshold matrix are printed on a print medium in an overlapping manner. In order to generate the threshold matrices, a first initial pattern being a dot pattern corresponding to a first grayscale value and a second initial pattern being a dot pattern corresponding to a second grayscale value lower than the first grayscale value are generated for pixel regions of the first and second threshold matrices. Then, thresholds of the first and second threshold matrices are set such that dot patterns having continuity with the first and second initial patterns are obtained at grayscale values between the first and second grayscale values.

A generation unit, which is configured to process image data to generate print data for applying an ink and a reaction liquid such that the print data corresponds to respective passes, generates print data for the ink such that the ink is applied only in a pass of which the elapsed time after application of the reaction liquid to the print medium is equal to or longer than the first time and shorter than the second time. The first time is from the timing where the reaction liquid is applied to the print medium up to the timing where adjacent droplets of the applied reaction liquid come into contact with each other and coalesce to form a reaction liquid film. The second time is from the timing where the reaction liquid is applied to the print medium up to the timing where the formed reaction liquid film is dissolved.

A technique capable of suppressing a color shift caused by a variation in ejection characteristics among nozzles is to be provided. A generating unit configured to generate print data which is configured with a printing pixel, which represents that a printing agent is applied, or a non-printing pixel, which represents that a printing agent is not applied, generates the print data as follows: (i) the first quantization data is obtained by quantizing the first image data; and (ii) by applying a correction value based on the ejection characteristics related to a plurality of printing elements for applying a printing agent, a value representing that a printing agent is applied a plurality of times is set for at least one target printing pixel in the first quantization data.

A method of controlling a printer is described, for printing a pattern from a first row of fluid ejection nozzles and a second row of fluid ejection nozzles in a multi-pass printing mode. The first and second rows of fluid ejection nozzles eject fluid of a first type and fluid of a second type, respectively. The method comprises: assigning respective parts of the pattern to be printed to the first and second rows of fluid ejection nozzles; applying a first mask to the first row of said ejection nozzles and a second mask to the second row of fluid ejection nozzles for printing with selected nozzles of each of the rows of fluid ejection nozzles during each pass; wherein the first mask comprises a mesa portion and the second mask comprises a mesa portion wherein the mesa portion of the first mask includes at least a first peak and the mesa portion of the second mask includes at least a second valley, the first peak overlapping with the second valley.