Contrast Ratios Run Amok

Ridiculous Display Contrast Ratios

Ok, I can buy into 3000:1 or even slipping by 10000:1 (yikes) contrast ratios for the latest LCD or plasma displays, but hey guys, this is getting to be too much when I saw an ad from a local electronics shop the other day touting 2,000,000:1, yes that’s 2 million to one ratio.  What are we looking at the sun?

Using accepted scientific methods to measure realistic contrast ratios for displays, a figure of 2,000,000:1 would burn your retinas out.  Numbers between to 20:1 and 100:1 are more the norm believe it or not.  The unscientific off the wall methods used to come up with these ridiculous numbers is in the mind of some very colorful marketing types to say the least, who seem to get away with outlandish claims.  Consumers can’t be that gullible, can they!  Big numbers always play well for certain marketing strategies.

Contrast ratio is a measure of how much difference there is between the brightest and darkest spot or area on a display, not to be confused with dynamic range.  At 2,000,000:1, that represents a 21 bit equivalent range of light to dark.  That’s smoking some real high quality drapes and some.

Gamma corrected digital video data presented to a display in RGB form is only 8 bits per pixel.  Hmmmm, that’s only a 256:1 grayscale range.  Grayscale range is what really matters.  The more bits the more gradients in tones and color shading within the image.  Eight bit depth is all there is in the video source material presented to a display, whether it comes from DVD, Blu ray, cable or from satellite.  Of course with some clever image processing, the image can be synthetically manipulated for perceived improvement, but it is still 8 bits per pixel.

While it’s true that one’s eyes can operate at about 1,000,000:1 or better, but only when exposed to well lit subjects in a narrow field of view.  Normally, the lightness range of the human eye can operate between about 180:1 and 300:1 at best under normal lighting conditions and more critically in wide field of view operation like when watching a TV screen.

There are so many variables to how your eyes perceive lightness and contrast of an image, that coming up with a solution that is real and can generate very pleasing and comfortable video to watch is not as dramatic as seeing a value of 2,000,000:1.

The only thing that matters is what your eyes see.  Fudged numbers for marketing reasons just doesn’t cut it.  Even when a display that can dramatically out do the capability of your eyes can only create serious eye fatigue and maybe damage.  That’s why numbers like 2000000:1 is just plain stupid.