Patent ID: 7821672
Filing Date: 2010-10-26
Classification: H04N

Abstract:
1. An image recording method of recording a halftone image representing a color original image by comparing said original image with a threshold matrix for each color component in an image recording apparatus comprising a head having a plurality of dot output elements for recording dots to a plurality of dot recording positions, respectively, arranged in a width direction perpendicular to a predetermined scan direction on an object to be printed or an object used in printing and a scanning mechanism for moving said plurality of dot recording positions on said object relatively to said object in said scan direction, comprising the steps of: a) preparing a first threshold matrix of a first color component which is generated in a matrix area of said first color component by setting a plurality of first halftone cells based on a plurality of first base points and setting threshold values so that halftone dot areas grow in accordance with shapes of said plurality of first halftone cells with increase of gray level of said first color component, said matrix area of said first color component being defined in a column direction corresponding to said scan direction and a row direction corresponding to said width direction, an average of intervals of said plurality of first base points being maximum with respect to a first direction tilted relatively to said column direction and being minimum with respect to a direction orthogonal to said first direction, said plurality of first base points being arranged randomly; b) preparing a second threshold matrix of a second color component which is generated in a matrix area of said second color component by setting a plurality of second halftone cells based on a plurality of second base points and setting threshold values so that halftone dot areas grow in accordance with shapes of said plurality of second halftone cells with increase of gray level of said second color component, said matrix area of said second color component being defined in said column direction and said row direction, an average of intervals of said plurality of second base points being maximum with respect to a second direction which is tilted relatively to said column direction and is different from said first direction and being minimum with respect to a direction orthogonal to said second direction, said plurality of second base points being arranged randomly; c) recording a predetermined pattern on an object with use of said first threshold matrix by said head and measuring print densities in a plurality of positions in said width direction of said predetermined pattern on said object or a material printed by using said object, to acquire a plurality of first modification coefficients for said plurality of positions; d) recording a predetermined pattern on an object with use of said second threshold matrix by said head and measuring print densities in a plurality of positions in said width direction of said predetermined pattern on said object or a material printed by using said object, to acquire a plurality of second modification coefficients for said plurality of positions; e) modifying element values of said first threshold matrix or pixel values of said first color component in said original image by using said plurality of first modification coefficients; f) modifying element values of said second threshold matrix or pixel values of said second color component in said original image by using said plurality of second modification coefficients; g) performing output control of a plurality of dot output elements for said first color component in accordance with comparison results between respective pixel values of said first color component in said original image and element values of said first threshold matrix corresponding to said respective pixel values, while moving a plurality of dot recording positions for said first color component relatively to an object to be printed or an object used in printing in said scan direction; and h) performing output control of a plurality of dot output elements for said second color component in accordance with comparison results between respective pixel values of said second color component in said original image and element values of said second threshold matrix corresponding to said respective pixel values, while moving a plurality of dot recording positions for said second color component relatively to said object in said scan direction.