Dell 1220 User Manual

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Glossary 51ANSI Lumens — A standard for measuring the brightness. It is calculated bydividing a square meter image into nine equal rectangles, measuring thelux (or brightness) reading at the center of each rectangle, and averagingthese nine points.Aspect Ratio — The most popular aspect ratio is 4:3 (4 by 3). Earlytelevision and computer video formats are in a 4:3 aspect ratio, whichmeans that the width of the image is 4/3 times the height.Brightness — The amount of light emitted from a display or projectiondisplay or projection device. The brightness of projector is measured byANSI lumens.Color Temperature — The color appearance of white light. Low colortemperature implies warmer (more yellow/red) light while high colortemperature implies a colder (more blue) light. The standard unit for colortemperature is Kelvin (K).Compressed Resolution — If the input images are of higher resolutionthan the native resolution of the projector, the resulting image will bescaled to fit the native resolution of the projector. The nature ofcompression in a digital device means that some image content is lost.Contrast Ratio — Range of light and dark values in a picture, or the ratiobetween their maximum and minimum values. There are two methodsused by the projection industry to measure the ratio:1 Full On/Off — measures the ratio of the light output of an all white image(full on) and the light output of an all black (full off) image.2 ANSI — measures a pattern of 16 alternating black and white rectangles.The average light output from the white rectangles is divided by theaverage light output of the black rectangles to determine the ANSI contrastratio.Full On/Off contrast is always a larger number than ANSI contrast for thesame projector.dB — decibel — A unit used to express relative difference in power orintensity, usually between two acoustic or electric signals, equal to tentimes the common logarithm of the ratio of the two levels.Diagonal Screen — A method of measuring the size of a screen or aprojected image. It measures from one corner to the opposite corner. A 97 Appendix: GlossaryDownloaded From projector-manual.com DELL Manuals