Image processing apparatus, method, and computer storage medium configured for line correction based on a number of linked dots

An image processing method for correcting multivalued data on which halftone processing has been performed, the method comprising the steps of:

• inputting multivalued data of a correction line to be corrected among the multivalued data;
• inputting multivalued data of a precedent line that precedes the correction line by N lines;
• detecting a number of linked dots, wherein the number of linked dots indicates how many pixels having a pixel value that is equal to or greater than a predetermined threshold value are linked in the multivalued data in a sub scanning direction from a bottom-end edge located closest to the correction line to the correction line;
• determining whether to correct each pixel in the correction line based on the detected number of linked dots;
• and
• correcting the multivalued data of the pixel in the correction line determined to be corrected,
• wherein the detecting the number of linked dots includes counting pixels having a pixel value that is equal to or greater than a predetermined threshold value and controlling a counter value of a counter based on a result of detecting pixels having a pixel value that is less than a predetermined threshold value between the correction line and the precedent line, so as to detect the number of linked dots that are linked from a side of the correction line to the bottom-end edge in the sub scanning direction, and
• the bottom-end edge is an edge at which the density becomes lower in the sub scanning direction and the lower of density values represents the background color.

A non-transitory computer readable storage medium storing a program that, when executed, causes a computer to perform

• inputting multivalued data of a correction line to be corrected among the multivalued data;
• inputting multivalued data of a precedent line that precedes the correction line by N lines;
• detecting a number of linked dots, wherein the number of linked dots indicates how many pixels having a pixel value that is equal to or greater than a predetermined threshold value are linked in the multivalued data in a sub scanning direction from a bottom-end edge located closest to the correction line to the correction line;
• determining whether to correct each pixel in the correction line based on the detected number of linked dots;
• and
• correcting the multivalued data of the pixel in the correction line determined to be corrected,
• wherein the detecting the number of linked dots includes counting pixels having a pixel value that is equal to or greater than a predetermined threshold value and controlling a counter value of a counter based on a result of detecting pixels having a pixel value that is less than a predetermined threshold value between the correction line and the precedent line, so as to detect the number of linked dots that are linked from a side of the correction line to the bottom-end edge in the sub scanning direction, and
• the bottom-end edge is an edge at which the density becomes lower in the sub scanning direction and the lower of density values represents the background color.