ADJUSTMENT FOR RECORDING POSITION SHIFT AT BIDIRECTIONAL PRINTING USING REFERENCE CORRECTION VALUE AND RELATIVE CORRECTION VALUE

摘要

PROBLEM TO BE SOLVED: To ease a recording position shift in a main scanning direction between a first half and a second half of bidirectional printing and improve an image quality by setting a reference correction value in relation to a specific reference dot, and determining an adjustment value in accordance with a first adjustment mode in which the reference correction value is corrected with a relative correction value preliminarily prepared for correcting the reference correction value. SOLUTION: When longitudinal ruled lines are recorded in parallel to a sub scanning direction with a black ink K and a cyan ink C in a first half and a second half of reciprocation, a positional shift related to black dots is solved by correcting with a reference correction value. A positional shift of cyan dots increases if the longitudinal ruled lines of cyan dots are printed in an equal adjustment state. A shift adjustment with a relative correction valueΔin relation to cyan dots is carried out in addition to the adjustment with the reference correction value, whereby positional shifts of black dots and cyan dots are reduced to an almost equal level. The positional shift of color ink dots can be prevented from excessively becoming large and a quality of color images is improved.