When three primary color inks and a particular color ink having a hue
different from those of the three colors are used, the number of passes
with regard to the same printing area is changeable, thereby speeding up
a printing operation and improving color development at a gamut expressed
by the particular color ink to achieve high quality images. Use or
non-use of the particular color ink is switched according to the number
of passes corresponding to quality information. If a high speed data
generation processing is not required but sufficient color development is
achieved, namely if the number of passes is large, the use of the
particular color will expand the color reproduction gamut. If the high
speed is required, namely if the number of passes is small, non-use of
the particular color ink will reduce the number of colors of the usable
inks.