Abstract
By the spread of portable digital cameras and of the cellular phones with the camera, the opportunities of image capturing has been increasing. The contrast of a captured image is often poor by capturing environment. In this case, a method to improve the contrast of a digital color image is required. This paper proposes a method to improve the contrast of a color image by optimizing a relation between inputs and outputs of color brightness based on the evaluation of color and special features including in the output image. The genetic algorithm that controls the selection of individuals by the difference of hues between an original image and an output image is used as the optimizing method. The liner differential value, the quadratic differential value and the entropy about the distribution of liner differential values in an output image are used for evaluating an individual fitness. The visual experimental results by the subjects show that the natural output images with the improved contrast and without the color changing were generated by the proposed method.