The Lumens test measures the number of lumens cast on-screen by each projector. Therefore, we took the average lux of the nine points and multiplied the result by 1.6875 to generate the lumens score. For the Contrast Ratio test, we measure light output at 16 points on a checkerboard image made of black and white blocks, then calculate average scores for all the white and all the black squares. We then divide the average white score by the average black score to indicate how much brighter the white blocks are when compared with the black blocks. The result is the contrast ratio.
Higher numbers are better, since they represent more dramatic contrast.
For the Brightness Variance test, we use the same nine lux measurements taken for the Lumens test and divide the maximum reading by the minimum reading to give a measure of how uniform the light output is. We created the image signals using a Pentium computer with a standard XGA-capable graphics adapter. The room was darkened to eliminate any light from sources other than the projector, and the image was projected onto flat-black paper so that minimal light would be reflected around the room. We took light measurements using a Tektronix J17 read-out base having a J1811 measurement head, with the light sensor held against the target wall and aimed directly at the projector. We measured the amount of light falling on that spot in lux, and took measurements at the points described in the ANSI test protocol.