| 主权项 |
1. A dither mask generation method used in halftone processing, the method comprising:
a nozzle relative ejection rate setting process of setting a nozzle relative ejection rate which is a control target of a nozzle ejection rate of each nozzle indicating a ratio of recording pixels for which each nozzle ejects ink to record a dot, in recording attending pixels allocated to each nozzle as pixels for which each of a plurality of nozzles in a recording head having the plurality of nozzles that eject ink is in charge of recording, and which stipulates a relative using ratio of the individual nozzles; a nozzle pattern setting process of setting a nozzle pattern indicating correspondence relation between the individual pixels of the dither mask and the nozzles in charge of recording at respective pixel positions; a nozzle ejection rate limiting process of setting an upper limit lower than a highest nozzle ejection rate to the nozzle ejection rates of the individual nozzles for each raster for the individual rasters in a main scanning direction, regarding at least some thresholds set to the individual pixels of the dither mask; and a threshold setting process of setting the thresholds to the pixels of the dither mask based on the nozzle relative ejection rate, the nozzle pattern and a limitation by the upper limit. |
