When determining that the head line in image display region 21 has the correlation with the first comparison reference line, controller 30b controls gate driver 25 and the source driver 24 to write the data voltage corresponding to the first comparison reference line in the head line. When determining that the head line in image display region 21 does not have the correlation with the first comparison reference line, controller 30b sets the head line to the first comparison reference line, and controls gate driver 25 and source driver 24 to write the data voltage corresponding to the head line in the head line.
Consequently, the appropriate data voltage can be written to the head line according to the determination of the correlation with the first comparison reference line.
Controller 30b sequentially determines whether pixel row 22 has the correlation with the first comparison reference line for every pixel row 22 including the first pixel row. When the first pixel row becomes pixel row 22 in which the correlation is determined, controller 30b stops the determination of the correlation with the first pixel row, and sets the first pixel row to the first comparison reference line again.
Consequently, the first pixel row that is originally set to the first comparison reference line in the frame is prevented from being not set to the first comparison reference line due to the setting of the head line to the first comparison reference line. Thus, the image quality degradation generated by the improper setting of the first comparison reference line can be prevented.