Color Image Enhancement by Using Hue-Saturation Gradient

It is necessary to preserve the hue component of color image in color image processing. Although the hue component can not be processed, it can be used for color image processing. However, the hue component has not been used for color image processing until now. It is already known that saturation components work effectively in color image enhancement. Therefore, in this paper, we define the hue-saturation gradient which is a gradient combining the saturation gradient and the hue gradient. The differential hue-saturation histogram equalization with variable enhancement degree (DHSHEwVED) is proposed. The proposed method can emphasize both intensity and saturation. The proposed method has two parameters, which can be used to adjust the contrast and colorfulness independently. We shows the effectiveness of proposed method from image processing results.