A display panel driver includes an image data generator, a brightness correction circuit performing a correction calculation on image data, a drive section driving the display panel in response to corrected image data; and a display timing generator outputting a timing control signal. The correction calculation by the brightness correction circuit is adjustable. When the display panel driver is placed into a test mode, the display timing generator is configured to output an internally-generated timing control signal and the image data generator outputs internally-generated evaluation image data. The evaluation image data are generated so that the evaluation images are switched from one to another in response to the internally-generated timing control signal.