TV makers go ape for 100Hz LCDs
But should consumers be as keen?
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Almost every TV maker exhibiting at the IFA consumer electronics show in Berlin last week used the event to launch LCD TVs capable of a picture refresh rate of 100 images a second. You couldn't move for bright-eyed booth staff there to demo 100Hz technology and persuade us to replace our LCD TVs already.
Toshiba's 32in 32WLT68 LCD: 100Hz technology on board
Looking at the many demos, it's not hard to see why. The benefits were there to see right in front of your eyes: sharper pictures, with clearer and better-defined surfaces, and smoother movement than you get from today's LCD screens.
Well, almost. For example, both JVC and Panasonic had 37in LCD TVs on their stands, each running at 100Hz. We could easily see the improvements the faster refresh rate made, but unfortunately only if we were within a cat's whisker of the screen, which is how most IFA attendees were eyeing the tellies. While flowers or buildings stood out more clearly than than they did on the old-style 37in displays set-up as a comparison, our eyes just couldn't pick-up that improvement when more than a couple of metres away from either 100Hz screen.
Here's the deal. Current LCDs refresh the picture at a rate of 25-60Hz, depending on whether they're aimed at the European or US markets, respectively. They essentially operate at the same rates as the HD source material: 25fps or 30fps for 720p and 1080p content, and 50 or 60 fields per second for 1080i pictures. Each field comprises only half the picture, so those 50Hz and 60Hz interlaced - hence the 'i' - are effectively 25 and 30 complete images per second.
Samsung's 100Hz F9 series
Moving up to 100Hz means running the source at 100 fields per second or 50fps. Since there aren't that many fields or frames in the source material, the TV has to invent them, using complex calculations to work out what the extra frames and fields look like.
So if a soccer ball moves eight pixels from left to right between frames one, two and three, the TV can generate two extra frames between one and two, and two and three, in which the ball moves four pixels. The result: five frames in which the ball moves a total of eight pixels, but it does so, to the eye, more smoothly than before.
The upshot, the various vendors claimed, is an end to the ghosting effect sometimes seen in LCD TVs: that slight blurring of moving images caused because the new image is drawn even before the old one has faded away.
Sony's 100Hz Bravia KDL-46V3000 LCD
Some TVs we saw did a better job than others, though with demo images it's always hard to be sure the manufacturer hasn't simply picked a sequence that shows the improvement rather better than a typical HD TV broadcast would. And, again, how much difference it makes when you're sitting on your sofa, well away from the screen will be entirely subjective.
And that's the crucial point: try before you buy. Does 100Hz technology make for smoother motion and thus a better picture? Yes. Will it make for an improved home viewing experience? Possibly. Take a look at the screen in a shop, running real TV programmes, first and then make up your mind.
COMMENTS
Film is very slow
Motion picture film used to be very slow. Trying to squeeze through more frames in a second may not have allowed enough light to fall on the film to properly expose the image. I assume however that film technology has moved on, but unfortunately there is still this legacy issue to deal with. Some of these digital picture analysers (see Snell & Wilcox) are in the tens of thousands of pounds and there is no way even Sony are putting that kind of power into a £2000 TV set. What can they do anyway when the original to-digital transfer is done badly anyway?
For years they have been advertising HDTV sets in Taiwan and China (where I live) for you to watch your horribly compressed NTSC MPEG-1 cable TV on. Hilarious. An ITT tube set from 1978 gives a much more appropriate picture quality for this sort of junk-quality source material. (My folks in the UK still have such a set, and as a PAL TV it gives a much better picture than is necessary for the NTSC cable broadcasts I watch in Taiwan!)
Direct MPEG interpolation
Further to the problems highlighted with direct MPEG interpolation: how do you get that information into a TV? Unless it has an inbuilt DVD player and cable/satellite decoder there’s no way it can be done. All it can do is interpolate the video stream as it comes in.
As for processing power: I use Elecard Moonlight player to ‘double frame rate’ convert my 1080I30 sources to effectively 1080P60 - all I can say is wow!! However, it needs all of my (fairly modern) PC processing power to do it in reatime – and that’s just filling in the alternate lines. Imagine what full frame interpolation will need; I sincerest doubt a quality realtime frame interpolator squeezed into a TV will be of good quality, certainly not for a reasonable price anyway. Granted specialised hardware could do it, but that won't be cheap either.
Let’s cut out the middleman – let’s process video at 60FPS.
Matthew Smith,
I thought movie cameras and cinema projectors were going all-digital? If so all mechanical shutter problems will be eliminated.
faster sources for the win
Nonsense to the people who say 24fps is optimum. It nearly always takes me a few minutes to get used to the horribly slow frame rate at the cinema. I use a 21" trinitron at a rock-solid 85Hz all day at work. I'm not hyper-sensitive, although I do notice 60Hz CRT computer screens.
Anyway, I always thought the 100Hz TVs just refreshed the same image faster, like a video 24fps inside a window on a computer a much faster refresh rate. If they are doing temporal interpolation I am very disappointed, no matter how clever they are. It means you really can't trust the what you see on TV to be the truth! Speed up the sources.
And on the 'filmified' Red Dwarf: it looked appalling. It even made the lame jokes worse. A bit like Hyperdrive. And Dr Who. None of which benefitted in any way from being 'filmified'. I think they look worse for it and we'll look back at this trend like we look back at the horrendously over-lit colour TV of the late 70s and early 80s.
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