Patent ID: 7447356

Claim:
An image signal correction method, for correcting luminance signals input for three colors in accordance with at least two different gray-level correction functions, comprising the steps of: calculating a correction coefficient common to the luminance signals input for the individual colors, employing the gray-level correction functions for the individual colors; and multiplying the luminance signals input by the correction coefficient, wherein, when the luminance signals input for three colors are respectively A 1 , A 2 and A 3 , and the gray-level correction functions for the individual colors are respectively f 1 (x), f 2 (x) and f 3 (x), the correction coefficient C meets: C = A 1 · f 1 ⁡ ( A 1 ) + A 2 · f 2 ⁡ ( A 2 ) + A 3 · f 3 ⁡ ( A 3 ) A 1 2 + A 2 2 + A 3 2 . ( Expression ⁢ ⁢ 1 )