Coordinates in an image and its corresponding color-converted data are supplied to a control/operation portion for every pixel. Quantization is applied to each color. The quantization is carried out so that a kind of dot for at least one color is made different from kinds of dots for the others in one and the same pixel when dots for different colors are superimposed on the pixel. The control/operation portion refers to a two-dimensional matrix on the basis of the quantization result, determines an output dot for each color, and converts the data into data which can be processed by a printer. The printer records an image based on the quantization result while reciprocating a recording head. Thus, it is possible to reduce color shift caused by the difference of the ink landing order at the time of reciprocating the head for recording.
