US Patent 7946678 Printing apparatus and data processing method

In the case where a multipass printing and an interlace printing are used together, the present invention enables outputting an image of good quality independently of the relation between the number of passes in the multipass printing and increase in the resolution in the sub-scanning direction through the interlace printing. Data processing is executed while pixels of inputted image data are made to correspond to two or more rasters in the sub-scanning direction, so that the dots are arranged in these rasters at a substantially equal rate, in the case where the number of print scannings to be executed multiple times is not an integral multiple of the number of rasters.