With an ink jet head having for each color two parallel columns of nozzles arranged shifted by one-half the pitch, odd-numbered rasters and even-numbered rasters are printed by the two nozzle columns. The registration between the odd- and even-numbered rasters is secured during the printing to produce a high quality image. The ink ejection timing between the two raster groups is shifted by a predetermined interval to form adjustment patterns; the adjustment patterns are checked and, according to the check result, an adjustment value for the ink ejection timing between the two ink nozzle columns is entered, and the entered adjustment value is stored to be reflected on the actual printing operation. To facilitate the adjustment pattern check, the adjustment patterns have a dot distribution with a blue noise characteristic at a resolution at which the printing apparatus can print.