Amount of detail that can be perceived in a diagonal direction. Although diagonal resolution is a consequence of horizontal and vertical resolution, it is not automatically equivalent to them. In fact, ordinary television systems usually provide about 40 percent more diagonal resolution than horizontal or vertical. Many ATV schemes intentionally sacrifice diagonal resolution in favor of some other characteristics (such as improved horizontal or vertical resolution) on the theory that human vision is less sensitive to diagonal resolution than to horizontal or vertical. There is some evidence that diagonal resolution could be reduced to about 40 percent less than either horizontal or vertical (overall half of its NTSC value) with no perceptible impairment. See also Resolution.