120Hz TVs: That Just Doesn't Look Right!

[Jason Dunn]

<p><img src="http://images.thoughtsmedia.com/resizer/thumbs/size/600/dht/auto/1225754207.usr1.jpg" /></p><p>Chris' post on the <a href="http://www.digitalhomethoughts.com/news/show/91154/mitsubishi-tv-with-freaking-laser-beams.html" target="_blank">Mitsubishi LaserVue TVs</a> reminded me of something I've wanted to post about for a while: I really dislike the way TVs with 120Hz refresh rates look. My local home theatre store, a <a href="http://www2.visions.ca/default.aspx" target="_blank">Visions</a> branch, had the same movie playing on two different TVs. One was a Pioneer Kuros at 60Hz, and one was an LG at 120Hz. The movement of the actors on the screen of the 120Hz TV looked completely bizarre. I thought at first it was just one of those "you're not used to it yet" types of things, but the more I watched it, and compared it with the 60Hz that I was used to the more I thought it just looked...wrong. The movement was exaggerated and, frankly, unrealistic. This is obviously the way TVs are moving, so ultimately I might have to get used to it, but I'm sure not excited about that prospect. On 120Hz TVs, can you toggle it back to 60Hz? Where do you stand on 120Hz TVs? Did I just not give it enough of a chance? Or do things at 120Hz look as bizarre as I think they do? Sound off...</p>

[Felix Torres]

Most odd...
Can you specify "how" it looks wrong?
Is it judder?
(plus 120Hz is an lcd tech and the Kuros are plasma, no?)
Still...

First are you sure the 120Hz feature was actually enabled?
Second, did they say what kind of source material they were playing?
Third, what kind of lighting did they have at the showroom? (Showrroms are notoriously bad places to gauge image quality...)
Fourth, I would dig up (online) how that particular model processes video.
Remember, the purpose of 120Hz is to ease the rendering of 24Hz content.
At its most basic, a 120Hz display, when fed 24Hz content properly, simply flashes the full content frame for five refresh frames. When fed 60Hz content it can display each frame (or field) twice.
Or, the display can get fancy:
For 60 Hz displays, some models interpolate every other frame, while others double-up the input, and others simply blank the screen every other frame (they claim it improves black levels and renders a more "tv-like" image because persistence of vision effects make it more like crts). Every vendor has their own approach and their own arguments. And that's just for 60hz.
Now, imagine the image processing tricks and approaches possible with 24Hz content and a 120Hz display. Lots of ways to go and lots of ways to go wrong.
Especially when different people have different persistence thresholds...
Every report I'm seen so far says 120Hz doesn't do much if anything to improve the video quality of most content but I don't recall anybody claiming it was visibly *worse*.
120 Hz displays aren't really ready for primetime (although being inherently 3d-ready might be excuse enough for some) but they shouldn't be offensively bad...
Really odd.
I'll have to see if I can track that model down, for curiosity's sake... :-D

[Pony99CA]

At its most basic, a 120Hz display, when fed 24Hz content properly, simply flashes the full content frame for five refresh frames. When fed 60Hz content it can display each frame (or field) twice.
But that means 120 Hz is basically useless.

Or, the display can get fancy:
For 60 Hz displays, some models interpolate every other frame, while others double-up the input, and others simply blank the screen every other frame (they claim it improves black levels and renders a more "tv-like" image because persistence of vision effects make it more like crts). Every vendor has their own approach and their own arguments. And that's just for 60hz.
Now, imagine the image processing tricks and approaches possible with 24Hz content and a 120Hz display. Lots of ways to go and lots of ways to go wrong.
Unless they're just showing the same frame again (see above) or displaying blank frames, any processing is really artificial pixels. Yes, sometimes it can make things look better (like dithering can help reduce the effect of jaggies), but it's still artificial.

Even 60 Hz progressive scan can be viewed as artificial depending on how it's done.

Steve

[Felix Torres]

Hey, I merely pointed out *how* they're using 120Hz panels, okay?
Doesn't mean I endorse it.:D

The thing to keep in mind about those "artificial pixels" that 120Hz nay-sayers always fallback on is that the 120 Hz issue isn't about *what* gets displayed but about *how* it gets displayed.

Remember, LCDs are by nature a *static* display technology; the image that gets displayed stays up, at full brightness, until it is replaced by a new image. Most people grew up with crts which are dynamic displays and rely on persistence of vision to maintain the image. 120Hz is a way for displays to "better" manage the transition between movie frames. Which is where interpolated and blank frames come in; blanking the screen results in a blinking display that feels more "natural" to people accustomed to crts and lets the eyeball-brain system do the interpolation. It does its best work with 60Hz content. Again, the intent isn't to "improve" the content; just to better manage how the viewer perceives the content.
Its really a human-factors thing; we're not perfect little image sensors.

The repeat frame approach achieves a different end result. There the intent is simply to take an incoming p24 signal and display it naturally with a minimum of processing. Normally, a 60Hz display, if fed a 24Hz signal has to run a frame-rate conversion called 2:3 telecine to turn the 24 incoming frames into 60 frames.
Telecine - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Telecine)
By going with a repeat-frame approach, the display can skip the telecine and give a "purer" image. Or, the repeat frames can be replaced with calculated frames intended to manage viewer perception, as above.

This telecine process and its inverse is the reason a *well-implemented* 1080i/60 data stream is 100% identical to a 1080p/24 data stream. A good movie player device (DVD, BD, whatever) will transmit *exactly* the same data via 1080i/60 as via 1080p24. Of course, that requires *quality* processing on both ends. Going with 24p output and 120Hz displays can skip the telecine processing altogether...

So, as you can see, there *is* a rationale for 120Hz displays. The problem is that, not only are viewers not perfect viewing sensors, we're imperfect in many different ways and to different degrees.

Ergo, "beauty is in the eye of the beholder"; there really is not golden standard for perception.

And that is why, in the real-world, 120Hz doesn't make much of a difference in image quality beyond, maybe, a placebo effect; anybody getting those high-end displays likely is connecting them to quality gear that does telecine well.

None of which explains how somebody, this side of The Flash, could see worse quality with 120Hz...:confused:

[Jason Dunn]

Most odd...Can you specify "how" it looks wrong?
Is it judder?

It's the motion of the elements on the screen - it looked fake. Not real. That's about the only way I can explain it. :)

[RACEMONEY]

I also have noticed this "not looking right" thing.....

I've never been able to quite put my finger on it....But I know it's there....

I always notice small things that just don't look right when someone enters a room and the actors head turns abruptly to look at them.......

Or the "shadows" that follow a sudden rapid movement of an arm or leg (On a UFC fighter for example)

I also have had a 3 or 4 inch horizontal band of colored lines that appears for a split second across the entire bottom ogf the screen since the first time I hooked this TV up. (Samsung LN-T4069F).

It started the first night we watched it back in July as a once or twice a day thing.

It has progressed to a 5 or 6 time a day thing now.....

I called Samsung 2 months ago....They sceduled a repair through a local shop...The parts were back ordered for 2 months now....

FINALLY!!! The repair guy came out yesterday that Samsung hired to replace the motherboard and the FRC (?) board.....

It worked when he left yesterday and about 5:30 yesterday afternoon.....No more TV.

All it does is turn itself on and off repeatedly and displays a really fuzzy looking green screen before turning itself off again....over and over again....

I called the repair people....they will order another motherboard....Should be there overnight.....Can't come out and replace it until Tuesday of next week....

Called Samsung.....Nothing they can do about it....Talked to Executive Customer relations.....Nothing they can do about it....

Frustrated..........

No TV all weekend??????!!!!!!!


I may actually have to talk to my wife....I'll probably be divorced by Tuesday....


Please help...........

[Jason Dunn]

No TV all weekend??????!!!!!!! I may actually have to talk to my wife....I'll probably be divorced by Tuesday....

Pretend you're going on vacation, a no TV vacation, but you're not leaving home. I'm sure you'll survive. :D