A display panel driver includes a color reducing circuit and a driving section. The driving section is configured to drive a first pixel and a second pixel. If a second input image data and a third input image data corresponding to the second pixel are supplied as an image data of a second image display format, then the color reducing circuit generates a third color reduction image data and a fourth color reduction image data. If the first input image data is supplied as the image data of the first image display format, then the first selector selects the third error value, and if the second input image data and the third input image data are supplied as the image data of the second image display format, then the first selector selects the second error value.