Hue-Preserving Color Image Enhancement on a Vector Space of Convex Combination Coefficients

The color image enhancement is one of the most important image processing techniques and is utilized to improve the visibility of digital images in various situations. In this paper, we propose a novel hue-preserving color image enhancement method which is executed on a vector space of convex combination coefficients and does not generate the color gamut problem. In the proposed method, at first, each pixel of an input image is represented by a convex combination of white, black, and its pure color. Then the combination coefficients are transformed by the histogram specification technique using the gradient norm-based weighted histograms of the coefficients, and the distributions of the coefficients are expanded to enhance the both of image intensity and saturation components appropriately. Through the experiments employing various color images, the effectiveness of the proposed method is verified.