Image recording method and image recording apparatus

An image recording apparatus for recording a halftone image representing a color original image by comparing said original image with a threshold matrix for each color component, 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;
• a scanning mechanism for moving said plurality of dot recording positions on said object relatively to said object in said scan direction;
• a first matrix memory for storing 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, intervals of said plurality of first base points being maximum with respect to a first direction tilted relatively to said column direction, said plurality of first base points being arranged randomly;
• a second matrix memory for storing 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, 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, said plurality of second base points being arranged randomly;
• a modification coefficient acquisition part for measuring print densities in a plurality of positions in said width direction of a predetermined pattern on an object or a material printed by using an object where said predetermined pattern on said object is recorded with use of said first threshold matrix by said head, to acquire a plurality of first modification coefficients for said plurality of positions, and measuring print densities in a plurality of positions in said width direction of a predetermined pattern on an object or a material printed by using an object where said predetermined pattern on said object is recorded with use of said second threshold matrix by said head, to acquire a plurality of second modification coefficients for said plurality of positions;
• a modification part for 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 and 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;
• and
• a control part for 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 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.