US Patent 7770993 Printing device and print image processing device

A printing device includes a print head having a plurality of nozzles capable of ejecting ink on a print medium and of forming one or more types of ink dots on the print medium; an ink dot setting unit that determines an ink dot setting for each pixel of image data by comparing a gradient of the each pixel with, from among thresholds in a matrix for each of respective pixels, a threshold corresponding to the each pixel of image data; a print head controller that controls ejection of ink from each nozzle of the print head on the basis of an ink dot setting determined by the ink dot setting controller; and a threshold matrix correction unit that corrects a predetermined threshold of the matrix depending on ink output characteristics of each nozzle of the print head.