That fraction of the high-light luminance required in a scene reproduced on a television display to convey the perception of black. The luminance of subjective black on a CRT has been studied by Lowry and Jarvis, who measured luminances on the original scenes, and compared the subjective appearance on a CRT display, as evaluated by viewing audiences. They found that the perception of black depends on a great many factors both in the reproduced scene and in the viewing conditions such as average scene reflection, luminance of areas adjacent to the display, etc. In most situation, luminance levels of 1/40 to 1/60 of the highlight luminance produce the perception of black even though the scene luminance range may reach 200:1 or more. It follows, then, that a scene element that is perceived as black may not necessarily be at reference-black level in a video signal.