A hue bar, radio buttons, and slide bars are laid out on an adjustment field of a dropout color setting screen. Hue which is continuously changed is displayed on the hue bar in a band form. The radio buttons correspond to specified color numbers so as to switch specification of a plurality of target colors. Sensitivity and intensity are set on the slide bars. Further, when the radio buttons are switched, a slider corresponding to the switched radio button, that is, the specified color number is switched to be in an active display such that a hue range is capable of being set and sliders corresponding to other specified color numbers are switched to be in a non-active display so that setting of the hue range is accepted. Further, settings of the sensitivity and intensity are accepted so as to be subordinate to the accepted hue range.