Contrast Ratio?

Question

When looking at the specs for new televisions, I see contrast ratios listed as "1500:1 contrast ratio" and "10,000:1 dynamic contrast ratio". Is there a difference between "contrast ratio" and "dynamic contrast ratio"?

Answer 1

Contrast ratio is the difference between the brightest image a TV can display versus the darkest image. Contrast ratio is measured one of two ways: full on/off (dynamic) contrast and ANSI (static) contrast.

With on/off contrast measuring, the light output from the TV is measured for an all-white (full on) image and compared to the light output for an all-black (full off) image. The difference in intensity is then reported as a ratio between those two images.

ANSI contrast measuring uses a white and black test pattern in a 16-square checkerboard that is displayed on the screen. The light output from a white area is measured and compared to the light output from a black area to get the contrast ratio.

ANSI contrast ratios are very small (say 1500:1) compared to off/on contrast ratios (usually greater than 15,000:1). So, TV manufacturers like to use the on/off (dynamic) contrast ratio in their specifications to make people think their product is better.

The human eye is capable of distinguishing images from a low end of near total darkness to a high end of bright sunshine. This results in a contrast ratio of about 10 million to one. But, it takes the human eye about 30 minutes to completely resolve to that contrast ratio. That is, if you go from bright sunshine to a very dark room, it takes about a half hour for the eye to fully adjust itself to near dark conditions. At any given time, the human eye can only resolve about a 400 - 800 : 1 contrast ratio.

So, any contrast ratio above about 1500:1 is really meaningless, especially the way they measure it.

Answer 2

The standard contrast ratio for movies [on standard dvds] is 2000:1.

Good luck!