Image processing apparatus and image processing method for forming a high-quality image by controlling superimposition of dots to be printed in multi-pass printing

摘要

This invention generates a high-quality image by controlling the superimposition relationship between dots to be printed in multi-pass printing by a printhead including a plurality of printing elements. When a yellow dot is printed after printing a cyan dot in one scan in multi-pass printing, image data serving as a processing target is generated as follows. In cyan and yellow halftone image data for each scan, halftone image data having dots at a common pixel are set to correspond to a scan in which yellow dot data precedes cyan dot data. A yellow dot is printed as a layer lower than a cyan dot.

主权项

1. An image processing apparatus which generates image data as a processing target by an image forming apparatus that forms an image by performing a plurality of times a scan in which, in a single region on a printing medium, a printhead including a plurality of printing elements prints in accordance with first image data corresponding to a first color component of an image, and prints in accordance with second image data corresponding to a second color component of the image, comprising:
a setting unit configured to set first scanning data and second scanning data in each scan for the first image data and the second image data, respectively, by dividing, for respective scans, density ranges represented by pixel values of pixels forming the first image data and the second image data, where each of the first scanning data and the second scanning data includes a lower signal value and an upper signal value of the divided density range; and a generating unit configured to generate, in each scan, first halftone image data corresponding to the first color component based on the lower and upper signal values of the first scanning data and a threshold matrix, and second halftone image data corresponding to the second color component based on the lower and upper signal values of the second scanning data and the threshold matrix, wherein the setting unit corrects the divided density range for the second image data to reduce an overlapped range between the density range of the first color component and the density range of the second color component in each scan and sets the first scanning data and the second scanning data in each scan for the second color component in accordance with the corrected density range, wherein, when there is a common density range between the density range represented by the first scanning data and the density range represented by the second scanning data for respective scans, said setting unit sets the first scanning data as a scan preceding the second scanning data.