Monitor definitions
BACKLIGHT
All LCD monitors require a source of light. The most common device to provide this
light is a device called a cold-cathode fluorescent lamp (CCFL. White LED backlights are one alternative
solution, found most commonly in laptop/notebook displays. Some high-end displays use RGB LEDs, which enable
them to deliver a wider color gamut. CCFL and both types of LED backlights have drawbacks: CCFL. backlights
deliver a narrower color range. The disadvantage is that LEDs can age at different rates, causing color and
white-point shifts over time.
COLOR DEPTH
Color depth indicates the number of bits the panel uses to represent the color of one pixel. A
display that uses eight bits each for the red, green, and blue channels (21 can produce 256 shades of each color
for a total of 16.777.216 colors (256x256x256). Most LCD monitors based on
twisted nematic (TN) technology, however,cannot transition eight bits per pixel quickly enough to compensate for
fast motion, resulting in unacceptable blurring and smearing while displaying movies and games. To get around this
problem, mass-market LCD panels use six bits per pixel (2') to represent the RGB color space. Since this reduces
the total number of displayable colors to just 262,144 (64x64x64), many panels use frame-rate control (a dithering
method) to have each pixel display a slightly different shade with each successive screen refresh.
Frame-rate control can enable a six-bit panel to simulate 16.194277
colors.
COLOR GAMUT
Color gamut describes a
subset of a defined color space that a display is capable of producing. Color gamut typacally is a percentage of
the NTSC (National Television System Committee) color space. A typical claim of the manufacturers is that their
displays delivered 72 percent of the NTSC color space.
CONTRAST RATIO
Contrast ratio is
supposed to measure the relative magnitude between the brightest (white) and darkest (black) colors the display can
produce. Unfortunately, the manufacturers' propensity for using different
methodologies and unstated variables in their measurements has effectively rendered this specification meaningless.
The Industry has further muddied the waters by introducing entirely new variations of
this measurement, such as dynamic contrast ratio. We recommend you ignore this spec when comparing LCD
monitors.
 
VIDEO INPUTS
Mostmonitors today support
the two most common digital video interfaces, DVI and HDIVSI (with HDCP copy protection. so you can watch Blu-ray
movies at full resolution using either one). In terms of analog display interfaces, every monitor has an
old-school VGA port, some monitors today also feature composite and component video inputs (useful for connecting
such analog sources as VCRs and older set-top boxes and DVD players). The S-Video input is now
obcolete.
PANEL TYPE
Virtually every consumer LCD
monitor uses thin-film transistor (ITT) technology these days. but it's important to consider the subsets of that
classification. Twisted nematic (TN) is the most common because
it's the easiest and least expensive to produce. TN panels boast very fast response times, but are typically
limited to six-bit color depth. The next two most common subsets are super in-plane switching (S-IPS. developed by
Hitachi, although LG also uses it) and super patterned vertical alignment (S-PVA, jointly developed by Samsung and
Sony). Both S-IPS and S-IPA panels support eight-bitcolor, but have much slower response times than TN
panels.
RESPONSE TIME
Response time measures how
long it takes an LCD monitor's pixels to transition from one state to another and is measured in milliseconds. A
monitor with a low response time will display fewer motion artifacts with movies and games.
STAND FUNCTIONS
Typical
LCD displays have a stand that tilts, where others have the features to swivel left to right while
others offer a height adjustment. NEC's EA241WM for example pivots to enable you to switch between landscape
and portrait modes.
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