| 摘要 |
A system of the present invention first refers to a table of a recording ratio with respect to a higher-density ink and determines whether or not deep dots are to be formed, based on input tone data, according to a systematic dither method. When it is determined that deep dots are formed, the system drives a piezoelectric element PE of an ink head corresponding to the higher-density ink to form deep dots and computes a resulting value RV of the deep dots. When it is determined that deep dots are not formed, the system sets the resulting value RV of the deep dots equal to zero, determines whether or not light dots are to be formed by a lower-density ink, based on the input tone data, according to an error diffusion technique, and computes a resulting value RV of the light dots. The on/off control of the light dots minimizes a density error or a difference of a resulting image from an original image. This structure enables a printer for printing images with a plurality of dots having different densities per unit area to appropriately determine the on/off state of the plurality of dots and thereby improve the printing quality. Another applicable structure makes the existence or non-existence of dots by an achromatic color ink reflect upon formation of dots by cyan ink.
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