Image processing apparatus determining finalized band data which is capable of being printed by one scanning of print head

An image processing apparatus comprising:

• a print execution machine having a print head configured to eject ink from a plurality of nozzles arranged in a subscanning direction and a conveyance machine configured to convey a recording sheet, wherein the print execution machine is configured to print an image on the recording sheet by scanning the print head a plurality of times in a main scanning direction perpendicular to the subscanning direction;
• a processor comprising hardware;
• and
• a memory storing computer-readable instructions therein, the computer-readable instructions, when executed by the processor, causing the image processing apparatus to perform:
• extracting, from image data representing an original image, provisional band data representing a provisional band image, the provisional band image being capable of being printed by one scanning of the print head, the provisional band image including a plurality of candidate lines, each of the plurality of candidate lines having a plurality of pixels arranged in the main scanning direction;
• identifying a target line from the plurality of candidate lines and a neighboring line neighboring the target line in the original image;
• calculating near white number for the target line, the near white number for the target line being number of pairs of a first pixel and a second pixel, wherein the first pixel is located on the target line, the second pixel is located on the neighboring line and in positionally adjacent relation to the first pixel, and at least one of the first pixel and the second pixel is a near white pixel, wherein the near white pixel is defined as a pixel satisfying at least one of a condition that a chroma value of the pixel is smaller than or equal to a chroma threshold value and a condition that a lightness value of the pixel is greater than or equal to a lightness threshold value;
• determining whether a prescribed boarder condition for the target line is met, wherein the prescribed border condition for the target line indicates that the near white number for the target line is greater than or equal to a first threshold value;
• in a case where the prescribed border condition is met for the target line, determining finalized band data representing a finalized band image, the finalized band image including at least part of the provisional band image, the finalized band image having the target line as a borderline, the borderline being closest to a border of the finalized band image, the finalized band image being capable of being printed by one scanning of the print head;
• outputting image data including band data based on the finalized band data to the print execution machine;
• and
• in a case where a specific condition is met, changing the target line to one of the plurality of candidate lines which is not selected as the target line, the specific condition including a condition that the prescribed border condition is not met for the current target line.

A method for controlling a print execution machine having a print head configured to eject ink from a plurality of nozzles arranged in a subscanning direction and a conveyance machine configured to convey a recording sheet, wherein the print execution machine is configured to print an image on the recording sheet by scanning the print head a plurality of times in a main scanning direction perpendicular to the subscanning direction, the method comprising:

• extracting, from image data representing an original image, provisional band data representing a provisional band image, the provisional band image being capable of being printed by one scanning of the print head, the provisional band image including a plurality of candidate lines, each of the plurality of candidate lines having a plurality of pixels arranged in the main scanning direction;
• identifying a target line from the plurality of candidate lines and a neighboring line neighboring the target line in the original image;
• calculating near white number for the target line, the near white number for the target line being number of pairs of a first pixel and a second pixel, wherein the first pixel is located on the target line, the second pixel is located on the neighboring line and in positionally adjacent relation to the first pixel, and at least one of the first pixel and the second pixel is a near white pixel, wherein the near white pixel is defined as a pixel satisfying at least one of a condition that a chroma value of the pixel is smaller than or equal to a chroma threshold value and a condition that a lightness value of the pixel is greater than or equal to a lightness threshold value;
• determining whether a prescribed boarder condition for the target line is met, wherein the prescribed border condition for the target line indicates that the near white number for the target line is greater than or equal to a first threshold value;
• in a case where the prescribed border condition is met for the target line, determining finalized band data representing a finalized band image, the finalized band image including at least part of the provisional band image, the finalized band image having the target line as a borderline, the borderline being closest to a border of the finalized band image, the finalized band image being capable of being printed by one scanning of the print head;
• outputting image data including band data based on the finalized band data to the print execution machine;
• and
• in a case where a specific condition is met, changing the target line to one of the plurality of candidate lines which is not selected as the target line, the specific condition including a condition that the prescribed border condition is not met for the current target line.