Patent ID: 8351695

Claim:
An image processing apparatus that performs tone conversion processing on a color image signal taken in from an imaging system, comprising: a color space conversion unit that converts the color image signal into a luminance signal and a color signal in a predetermined color space; a tone conversion unit that performs tone conversion processing on the luminance signal on the basis of a predetermined tone conversion characteristic; a function setting unit that sets a function for chroma correction processing using the luminance signal, the tone conversion-processed luminance signal, a maximum value of the luminance signal in the color space, and a luminance value when a maximum chroma is indicated in a hue region to which the color image signal belongs, as parameters; and a chroma correction unit that performs chroma correction processing on the color signal using the luminance signal, the tone conversion-processed luminance signal, and the function, and wherein the function setting unit uses a function indicated by the following equation: a · c · y 1 - b y 0 - d where a value of the luminance signal is set at y 0 , a value of the tone conversion-processed luminance signal is set at y 1 , and constant terms are set at a, b, c, d, as the function; and the function setting unit comprises: a hue information calculation unit that calculates hue-related information from the color signal; a threshold setting unit that sets the luminance value when the maximum chroma is indicated in the hue region to which the color image signal belongs as a threshold relating to the luminance signal and the tone conversion-processed luminance signal on the basis of the hue-related information; and a constant term definition unit that defines the constant terms a, b, c, d on the basis of the threshold and the maximum value of the luminance signal in the color space.