Difference between lumens and ANSI lumens
1.“Lumen” is the basic measure of luminous flux (the observed power or strength of light).
2.ANSI lumen is measuring lumen as stipulated by the ANSI standardization. Thus, it is more specific and accurate for determining the brightness of the projector.
You’ll be using “lumens” to express how much light a lamp – or another light source – produces, regardless of the direction that light goes into.
You’ll be using “ANSI lumens” to express how bright the image of a projector will be as a result of the output of the lamp inside that projector. Of course, there are other factors that define the brightness of the image. For instance, projecting a black powerpoint slide would not give a lot of brightness on the screen.
While a lamp manufacturer uses a laboratory setup to measure the entire light output to determine that output in lumen, projector makers follow an approach defined by the ANSI (the American National Standards Institute) in order to make projectors comparable to each other.
How? Put the projector in a room where the temperature is 77 Fahrenheit. Adjust brightness and contrast of the projector: you want to distinguish a 95% white block that covers 5% of the screen from another 100% white block and third block that is 90% white.
Brightness and contrast adjustments made? Good, now switch to a full white image and measure the output of the projector at nine specific locations as prescribed by ANSI. These are averaged and multiplied depending on the projection size. Voila: the brightness of the projector in ANSI lumen.
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