Color image enhancement based on Hue differential histogram equalization

Histogram equalization (HE) is one of the simplest and effective methods for contrast enhancement. The contrast of an image is increased by HE. But HE fails to produce satisfactory results for wide range of low contrast images, because HE does not use a spatial feature that is included in an original image. In order to overcome this disorder the differential gray-levels histogram equalization (DHE) has been proposed. In this paper, we extend the DHE to color image processing. Then, hue and intensity information are taken into account for color image enhancement. Hue component is used for intensity processing. Even by keeping the intensity constant we can capture the edge by changing the hue. First the processing is done with intensity component and then with hue component. Finally intensity and hue component results are combined to produce better results. The proposed method has one parameter which controls the enhancement property of the color image. The guideline for the decision of the parameter which is agreed by the human sense is also described.