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Posted by Rick Merrill on 08/01/07 22:56
Rick Merrill wrote:
...
> What is a 'dynamic' contrast ratio?
Found this,
Dynamic contrast ratio
A notable recent development in the LCD technology is the so called
"dynamic contrast" (DC). When there is a need to display a dark image,
the display would underpower the backlight lamp (or decrease the
aperture of the projector's lens using a shutter), but will
proportionately amplify the transmission through the LCD panel. This
gives the benefit of realizing the potential static contrast ratio of
the LCD panel in dark scenes, when the image is watched in a dark room.
The drawback is that if a dark scene does contain small areas of
superbright light, they may be sacrificed and blown out.
The trick for the display is to determine how much of the highlights may
be unnoticeably blown out in a given image under the given ambient
lighting conditions.
Brightness, as it is most often used in marketing literature, refers to
the emitted luminous intensity on screen measured in candela per square
metre (cd/m^2). The higher the number, the brighter the screen.
It is also common to market only the dynamic contrast ratio capability
of a display (when it is better than its static contrast ratio), which
should not be directly compared to the static contrast ratio. A plasma
display with a static 5000:1 contrast ratio will show superior contrast
to an LCD display with 5000:1 dynamic and 1000:1 static contrast ratio
when the input signal contains full range of brightnesses from 0 to 100%
simultaneously. However they will be on par when input signal ranges
only from 0 to 20% brightness.
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