HDTV Almanac - CES 2010: Here Comes 480 Hz!

[alfredpoor]

The arms race continues. When you have a product category where the competing products do not differ significantly, manufacturers must find a way to make their product stand out. Almost all televisions are now thin and flat and have 1080p resolution, so what can they do? Competing on price is difficult, with margins already cut [...]

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[jerfilm]

I kind of miss the logic of pooping up the refresh rate. Common sense tells me that the eye has a fairly low limit at which it can process images. So if an object streaks across the screen in one second, will it really matter much whether its broken down into 30 frames or 500? You still have one second to process it and it'll still be a blur. I think you're right, most folks will not have the capability of seeing the difference about 99% of the time. So what's the point??

[alfredpoor]

If I could have a nickel for each minute invested by standards committees on the subject, I'd be retired. A lot of debate has been held about the physiology and physics and related factors in the display and perception of moving images. Keep in mind that your local cinema shows movies at just 24 frames per second (24 Hz) with black frames inserted (at least if they're showing a film as opposed to a digital movie). But many people actually can notice the "jerkyness" of this and miss it when watching a standard DVD (which they say looks too much like "watching television").

One good source on the topic is the VESA Flat Panel Display Measurement (FPDM) Standards version 2.0 document, which includes information on how to measure pixel response time. You can find some information about the Motion Picture Response Time (MPRT) in this white paper from a metrology company: http://www.eldim.fr/library/eldim-produ ... ope-sa.pdf. And here's a paper that suggests a low-cost means of measuring MPRT: http://hal.archives-ouvertes.fr/docs/00 ... y_2007.pdf.

For me, the bottom line is that LCDs depend on the physical movement of liquid crystal molecules to make an image. Movement takes time. Increasing the frame rate acts like a strobe light in a disco, freezing the action, so you don't see a blur. Keeping the lights on while the molecules (or the movie film frames) move result in a blurred image. I know that I can see a distinct difference between 60 Hz and 120 Hz on an LCD for some types of moving images. I'm not sure at what point you start getting diminished returns for higher frame rates, but I suspect that it's probably around 120 Hz at this point.

Alfred

[BobDiaz]

For those who are "older", remember the transistor wars of the early 1960s?

Back then an AM Radio only needed 4 or 5 transistors, but manufacturers soon learned that people assumed more transistors = better radio. Thus, we soon saw, 6, 7, 8, 10, 12, 15, 20, and 30 transistor radios. The only problem was, it was a psychological gain, NOT a real gain in performance, but bigger numbers do impress.

Nice to know that 50 years later, NOTHING has changed.

Now one can make a case for 120 Hz, but 240 HZ or 480 Hz... Given that the human eye can not see beyond a 100 Hz refresh rate, what's the point?

What's next 960 Hz???


Bob Diaz

[alfredpoor]

For Detroit, it was horsepower. In the early days of PCs, it was MHz (clock cycles). Laser printers: dots per inch. Specmanship has been an integral part of American marketing forever, it would seem.

Don't bet against 960 Hz.

Alfred