An image processing method configured to produce image data output from an image forming apparatus configured to form an image by using a recording head composed of a liquid ejecting head having plural arranged nozzles configured to eject a liquid drop and an energy generating device configured to generate ejection energy corresponding to each nozzle while conducting a halftone processing configured to covert input image data to an N value which is less than a tone (M value) thereof (N value: M>N≧2) is provided, wherein a halftone processing configured to substantially reduce a driving frequency of a driving wave pattern applied to the energy generating device is conducted when a liquid drop with a drop size causing ejection irregularity or a liquid drop from a nozzle causing ejection irregularity is ejected.