For images with color, it seems obvious that an additional term must be added to consider the difference between the color of the background and the color of the target. In other words, if at present the contrast between the target and the background is an "intensity" contrast, the new contrast should contain a term including the "color" contrast.-For images with color, it seems obvious that an additional term must be added to consider the difference between the color of the background and the color of the target.　In other words, if at present the contrast between the target and the background is an "intensity" contrast, the new contrast should contain a term including the "color" contrast.