An image display apparatus includes: an image display panel having a two-dimensional matrix with (P×Q) pixels each including first, second and third sub-pixels for displaying respective first, second and third elementary colors, and fourth sub-pixel for displaying a fourth color; and a signal processing section configured to receive first, second and third sub-pixel input signals respectively provided with signal values of x1-(p, q), x2-(p, q) and x3-(p, q), and to output first, second, third and fourth sub-pixel output signals respectively provided with signal values of X1-(p, q), X2-(p, q), X3-(p, q) and X4-(p, q), which used for determining the display gradations of the first, second, third, and fourth sub-pixels, respectively, with regard to a (p, q)th pixel where notations p and q are integers satisfying equations 1≦p≦P and 1≦q≦Q.