Polaroid Polaview 335 XGA Manual page 28

Polaview 335 XGA and 235 SVGA
Super-Portable LCD Projectors
Glossary of Terms (cont'd)
Keystone Effect A distorted picture where one edge is not the same dimension as the opposite edge.
Typically results when the image is projected at an angle. In stone buildings, the tapered stone at the top of
an arch was the "key" that prevented the arch from falling.
Kilohertz (kHz) Thousands of Hertz, or a frequency rate in units of thousands of cycles per second. For
example: CGA's horizontal scan rate is 15,750 hertz (Hz), or 15.75 kHz.
LCD (Liquid Crystal Display) Display technology that relies on polarizing filters and liquid-crystal cells
rather than phosphors illuminated by electron beams to produce an on-screen image. To control the intensi-
ty of the red, green, and blue dots that comprise pixels, an LCD's control circuitry applies varying charges
to the liquid-crystal cells through which polarized light passes on its way to the screen. The amount of light
that makes it through to the screen depends on the amount of charge applied to the corresponding cell
before passes through a second polarizing filter and a red, green, or blue color mask.
Lumen A unit of measure for the amount of light emitted by a light source. Luminance This is the signal
that represents brightness in a video picture. Luminance is any value between black and white. Luminance
is abbreviated as "Y."
MHz An abbreviation for megahertz. This is a unit of measurement and refers to a million cycles per
second. Bandwidth is measured in megahertz.
Pixel A definable location on a display screen that consists of multiple or single triad of dots (red, green,
and blue). A computer picture is typically composed of a rectangular array of pixels (i.e. 640 x 480). The
resolution of a picture is expressed by the number of pixels in the display. For example, a picture with
560 x 720 pixels is much sharper than a picture with 275 x 400 pixels.
Saturation The intensity of the color is called saturation. Example: A lightly saturated red looks pink.
Fully saturated red is like the red of a crayon. Not to be confused with brightness, saturation is the amount
of pigment in a color, and not the intensity. Low saturation is like adding white to the color.
SVGA (Super Video Graphics Array) Also referred to an extension of the VGA video standard.
SVGA video adapters support resolutions of 800 x 600 pixels and higher with up to 16.7 million colors
(known as true color).
UHP Ultra High Power lamp
Vertical Rate (Frequency) The number of times the screen is refreshed per second. Typically shown as a
measure of hertz (Hz).
VGA (Video Graphics Array) Also referred to as Video Graphics Adapter. Introduced by IBM in 1987.
VGA is an analog signal with TTL level separate horizontal and vertical sync. The video outputs to a
15-inch HD connector, has a horizontal scan frequency of 31.5 kHz, and vertical frequency of 60 to 70 Hz
non-interlaced. The signal has a Pixel-by-Line resolution of 640 x 480 with a color palette of 16 from
256,000.
XGA (Extended Graphics Array) IBM's graphics standard that includes VGA and extended resolutions
up to 1024 x 768 pixels, interlaced, 35 kHz. An XGA video card has a 15-pin HD connector.
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