A Hue Preserving Image Enhancement Based on Multiple Parametric Sigmoid Functions in Each RGB Component

In this study, a new image enhancement method for digital color images is proposed. The proposed method realizes the lightness contrast enhancement and the image sharpening simultaneously and effectively while preserving hue of an input image. In the proposed method, concretely, the method based on the multiple parametric sigmoid functions is applied to each of R, G, and B components of the input image, and its outputs are fused by the geometrical processing so that the hue of the resultant image is the same as that of the input image. The effectiveness of the proposed method is verified by the experiments using various digital color images.