projectisle.com.au - Image Contrast Ratio

Contrast Ratio

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Simply put the Contrast ratio is ratio between white and black of the image on your screen. Essentially, the higher contrast on a projector increases the perception of depth in the image, and means subtle colour variations show up more clearly. Hence subtle textures are more visible. It also means that dark scenes can cope with more ambient light in the room.

There are two methods used to measure Contrast Ratio:

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Full On/Off contrast 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.

ANSI contrast is measured with a pattern of 16 alternating black and white rectangles. The average light output from the white rectangles is divided by the average light output of the black rectangles to determine the ANSI contrast ratio.

Full on/off contrast figures are much higher than ANSI contrast measurements. Never compare ANSI with full on/off figures.

To highlight the problem take a look at these two projectors, the HP SB21 has an ANSI contrast ratio of 450:1 and a Full on/Full off contrast ratio of 1800:1. If you now look at the NEC SX6000 it has an ANSI of 250:1 and a FO/FO of 400:1. So there is no correlation between the two!

Comparison Between Contrast Ratios:

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The ongoing war between LCD and DLP was all going DLP's way until the Sony VLP-HS50 and the Panasonic PT-AE700, both use dynamically reconfiguring variable aperture (iris), that adjusts to the brightness level of the image on a frame by frame basis. The VPL-HS50 has a staggering 6000:1 contrast ratio.

The Sony and Panasonic LCD releases will also have an impact on the perceived value of projectors across the entire price spectrum. For example, compare the Sony HS51 to the Marantz VP-124S. Both are 1280x720 resolution. Both have the same lumen output. The Marantz has a contrast of 3800:1. Both are extremely quiet. Both have HDMI and component video interfaces. Both have physical lens shift. The only obvious differences on the spec sheets are that the Sony is LCD while the Marantz is DLP. The prices? The Sony is $3,500 while the Marantz is $13,500. How many consumers are going to believe that there is a $10,000 differential in value between these two units? None simply because there isn't.