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Reference.org
Contrast ratio
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<p>The contrast ratio (CR) is a property of a display system, defined as the <a href="/facts/Ratio/mFmhQt7T">ratio</a> of the <a href="/facts/Luminance/yAqK94ny">luminance</a> of the brightest shade (white) to that of the darkest shade (black) that the system is capable of producing. A high contrast ratio is a desired aspect of any display. It has similarities with <a href="/facts/Dynamic_range/zxcuI4Fn">dynamic range</a>. </p><p>There is no official, standardized way to measure contrast ratio for a system or its parts, nor is there a standard for defining "Contrast Ratio" that is accepted by any standards organization so ratings provided by different manufacturers of display devices are not necessarily comparable to each other due to differences in method of measurement, operation, and unstated variables. Manufacturers have traditionally favored measurement methods that isolate the device from the system, whereas other designers have more often taken the effect of the room into account. An ideal room would absorb all the light reflecting from a <a href="/facts/Projection_screen/EfJYBwt2">projection screen</a> or emitted by a <a href="/facts/Cathode-ray_tube/8NVGx5C7">cathode-ray tube</a>, and the only light seen in the room would come from the display device. With such a room, the contrast ratio of the <a href="/facts/Image/hbjEdTXK">image</a> would be the same as the contrast ratio of the <a href="/facts/Display_device/yX1Mypk0">device</a>. Real rooms reflect some of the light back to the displayed image, lowering the contrast ratio seen in the image. </p><p>Static contrast ratio (or simultaneous contrast ratio) is the luminosity ratio comparing the brightest and darkest shade the system is capable of producing simultaneously at any instant of time, typically measured using ANSI checkerboard pattern; on the other hand, dynamic contrast ratio (or sequential contrast ratio) is the luminosity ratio comparing the brightest and darkest shade the system is capable of producing over time (or in one frame and another sequential frame), typically measured using the full on/full off method. Moving from a system that displays a static motionless image to a system that displays a dynamic, changing picture slightly complicates the definition of the contrast ratio, due to the need to take into account the extra temporal dimension to the measuring process. </p>