A driving method for an image display apparatus is disclosed. The image display apparatus includes an image display panel including a plurality of pixels each including first, second, third and fourth subpixels and arrayed in a two-dimensional matrix. A signal processing section determines an expansion coefficient based on a saturation value and a maximum value of brightness in an HSV color space expanded by addition of a fourth color to three primary colors. First to third correction signal values and a fourth correction signal value are determined based on the expansion coefficient, first to third subpixel input signals and first to third constants. A fourth subpixel output signal is determined from the fourth correction signal value and a fifth correction signal value determined from the expansion coefficient and the first to third subpixel input signals and output to the fourth subpixel.