Efficient luminance and saturation processing techniques for bypassing color coordinate transformations

In many applications of color image processing, only modification of the luminance component is desired. However, the commonly used coordinate systems, such as HSI, LHS, and YIQ, are not perceptually orthogonal; that is, luminance modification can cause perceptual shifts in the hue and saturation. In this paper, the authors present a theoretical analysis of this phenomenon. Efficient techniques are developed for bypassing the costly coordinate transformations when only the luminance or only the saturation is to be modified. Experimental results using histogram equalization support the theoretical analysis