A display driver comprises image processing circuitry and drive circuitry. The image processing circuitry is configured to output display image data representing a display image comprising an effective area to be displayed in a display area of a display panel and an invalid area not to be displayed in the display area. The drive circuitry drives the display panel based on the display image data comprising effective pixel data associated with first pixels included in the effective area and invalid pixel data associated with second pixels included in the invalid area. Effective pixel data associated with first pixels located within a boundary area adjacent to the invalid area is set to first grayscale values. The invalid pixel data associated with second pixels located within an insert area defined in the invalid area is set to second grayscale values comprising a value different from the first grayscale values.