Patent ID: 7537303

Claim:
A printing device which prints a color image to be printed on a printing medium by a printing head, the printing head having a plurality of nozzles corresponding to a plurality of colors of ink for forming a dot on the printing medium, the printing device comprising: an image data acquiring unit that acquires first image data having a plurality of pixel data; a nozzle information storing unit that stores nozzle information capable of identifying an abnormal nozzle related to banding among the plurality of nozzles; a second image data creating unit that creates second image data by changing a pixel value of pixel data corresponding to the abnormal nozzle related to the banding in the first image data based on the nozzle information, wherein the abnormal nozzle ejects ink of a first color; a printing data creating unit that creates printing data by converting the second image data into dot forming pattern data corresponding to each color of a color image so as to form the color image constructed by the second image data on the recording medium, wherein the printing data creating unit employs an N-value conversion processing unit that maps a range of a gray-scale level of a selected pixel of the second image data to one of a plurality predetermined values and that selects one of a plurality of predetermined sizes for forming a dot for the selected pixel in response to that predetermined value; and a printing unit that prints the color image constructed by the second image data on the recording medium by the printing head based on the printing data, wherein the second image data creating unit changes a pixel value of pixel data corresponding to the abnormal nozzle from a first value to a second value for at least reducing the banding, wherein the first value corresponds to a first non-zero ink ejection amount and the second value corresponds to a second non-zero ink ejection amount, wherein the second ink ejection amount is smaller than the first ink ejection amount, and wherein the second image data creating unit, after changing the pixel value of the pixel data corresponding to the abnormal nozzle, changes pixel values of pixel data corresponding to a plurality of second nozzles, wherein the plurality of second nozzles each are related to the abnormal nozzle and each eject ink of a different color, wherein the plurality of second nozzles and the abnormal nozzle print a image portion having a predetermined color and corresponding to the abnormal nozzle, wherein pixel values of the pixel data corresponding to the abnormal nozzle and the plurality of second nozzles are changed such that the actual printed color of the image portion is within the same color range of the predetermined color; wherein the printing device is a line-head-type printing device that is operable to print the color image in one pass.