Patent ID: 7755670

Claim:
A tone-conversion device converting a tone of an image generated from plural pixels having a signal component including an achromatic signal relating to brightness and a chromatic signal relating to color, said tone-conversion device comprising: a signal extracting unit which extracts said achromatic signal of a first pixel or a second pixel from said plural pixels as an achromatic signal value, the second pixel being in an immediate neighborhood of the first pixel; a neighborhood processing unit which generates a local signal of said first pixel according to said achromatic signal and said chromatic signal of a third pixel contained in a neighborhood area which is larger than said second pixel; a gain determining unit which determines a conversion gain for said signal component of said first pixel according to said achromatic signal value and said local signal; and a tone-conversion unit which converts said tone by multiplying, by said conversion gain, a signal component of said first pixel or a signal according to the signal component.