Patent ID: 8743156

Claim:
A driving method for an image display apparatus which includes (A) an image display panel wherein pixels each including a first subpixel for displaying a first primary color, a second subpixel for displaying a second primary color, a third subpixel for displaying a third primary color and a fourth subpixel for displaying a fourth color are arrayed in a two-dimensional matrix; and (B) a signal processing section; the signal processing section being capable of determining a first subpixel output signal at least based on a first subpixel input signal and an expansion coefficient α 0 and outputting the first subpixel output signal to the first subpixel; determining a second subpixel output signal at least based on a second subpixel input signal and the expansion coefficient α 0 and outputting the second subpixel output signal to the second subpixel; and determining a third subpixel output signal at least based on a third subpixel input signal and the expansion coefficient α 0 and outputting the third subpixel output signal to the third subpixel; the driving method being carried out by the signal processing section and comprising: (a) determining a maximum value V max (S) of brightness taking a saturation S in an HSV color space enlarged by adding the fourth color as a variable, HSV of the HSV color space standing for hue, saturation and brightness value; (b) determining the saturation S and the brightness V(S) of a plurality of pixels based on subpixel input signal values to the plural pixels; (c) determining the expansion coefficient α 0 based on at least one of values of V max (S)/V(S) determined with regard to the plural pixels; (d) for each of the pixels determining a first correction signal value based on the expansion coefficient α o , the first subpixel input signal and a first constant; determining a second correction signal value based on the expansion coefficient α 0 , the second subpixel input signal and a second constant; determining a third correction signal value based on the expansion coefficient α 0 , the third subpixel input signal and a third constant; determining a correction signal value having a maximum value from among the first, second and third correction signal values as a fourth correction signal value; and determining a fifth correction signal value based on the expansion coefficient α 0 and a minimum value from among the first subpixel input signal, the second subpixel input signal and the third subpixel input signal; and (e) determining, for each of the pixels, a fourth subpixel output signal from the fourth and fifth correction signal values and outputting the determined signal to the fourth subpixel.