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  Contrast Ratio


Contrast is the ratio between the brightest whites and darkest blacks in an image. The higher the contrast ratio, the bigger is the difference between the brightest whites and the darkest blacks of a projector.

The contrast ratio is expressed in numbers such as 500:1. It means that a projector with a 500:1 contrast ratio has its black level 500 times darker than its white.

How is contrast ratio measured?

The two methods the most used to measure the contrast ratio are "Full on/full off" and "ANSI Contrast".

  • Full on / full off: this method compares the light output of a completely white image (full on) and a completely black image (full off).
  • ANSI Contrast: this method uses a checker board of 16 black and white rectangles. The average light ouput from the white rectangles is then divided by the average light output from the black rectangles.

The ANSI contrast generally gives results 25% lower than the full on/full off method and not surprisingly manufacturers tend to favor the full on/full off method for their measurements.

Is contrast ratio an important factor?

The simple answer is not really.

The fact that different manufacturers use different measurement methods makes it difficult to compare different models and therefore makes the rating meaningless.

Also the numbers assume that you are using the projector in a perfect and controlled environment which is rarelly the case.
Any amount of ambient light would affect the contrast ratio since blacks can only be as black as the screen when no image is projected. The only way to get the full contrast as quoted by manufacturers is to be in a pitch black room with black surfaces and walls and only the projector on.

Finally other factors such as the projector brightness, or whether a projector uses an iris or if the white segment of the colour wheel can be turned off can make a difference to the projector performance.
And we haven't even talked about the fact that the human eye is so complex that it can't be compared to a digital measurement tool.


There is no need to pay over the odds for a projector just for a higher contrast ratio.