What does HD resolution really mean??

[frozentundra123456]

Hi all

Just a quick question. What does it take for a display (computer monitor, not TV) to be called HD? The reason that I ask is that now I am seeing a lot of displays at 1600x900 that are called HD or even HD plus. I have an old 19 inch acer monitor that is 1440x900. While it is fine for what I use it for (light gaming, internet, office tasks), I consider it fairly low end.
So to call 1600x900 HD seems overstatement to me. I thought you had to have 1080 for the vertical resolution to be called HD.

Anyway, if someone could clarify this, I would appreciate it.

 

[disappoint]

Technically 720p (720 lines of vertical resolution) or 1080i is HD. But 1080p is full HD.

so 1280x720 = minimum spec for it to be called HD
1920x1080 = full HD

480i is SD (standard definition)

the p stands for progressive, and the i for interlaced. Progressive means every line is rendered consecutively in 1 frame, and interlaced means every other line is rendered in 1 frame and every other line in the next frame. interlaced looks a bit choppy when there is movement or a lot of change from one frame to the next, progressive is smoother looking animation from one frame to the next.

Next we have the new 120hz monitors that are supposed to be even smoother for fast motion changes frame to frame. Unfortunately most screens that claim 120hz interpolate the frames in between and only accept a 60 hz input. Some new monitors coming out will accept a 120hz signal which is better and also useful for 3D.

TMI?

 

[Cogman]

HD = marketing scam for computer monitors
http://www.youtube.com/watch?v=mKYKyIObXyM

When referring to display screens, what disappoint said is correct. However, more then anything, it is marketing mumbo jumbo to try and hook people on "HD" displays which are supposed to be so much better then the regular ones (even though, as you've correctly pointed out, displays at HD resolutions have been around for a while. They just haven't always been called HD)

 

[Modelworks]

HD is the new 'Digital'

 

[Phynaz]

HD can mean anything from 704x576 to 7680x4320.

Disapoint, there is no such thing ad "full HD". HD is HD. Anything else is narketing.

 

[Jeff7181]

I'd still like to know how a 120 Hz (or 240 for that matter) TV can display a better picture than a 60 Hz TV when the SOURCE video is only 60 frames per second.

 

[edplayer]

I'd still like to know how a 120 Hz (or 240 for that matter) TV can display a better picture than a 60 Hz TV when the SOURCE video is only 60 frames per second.

Ask the person who told you that...

 

[Patrick Wolf]

I'd still like to know how a 120 Hz (or 240 for that matter) TV can display a better picture than a 60 Hz TV when the SOURCE video is only 60 frames per second.

Or Blu-Ray, 24Hz. 120Hz+ is simply a feature of preference that provides "smoother motion". Happily it's a feature that can be turned off. I think sports, nature shows, and video games "benefit" the most. But movies? No thank you.

 

[deimos3428]

I'd still like to know how a 120 Hz (or 240 for that matter) TV can display a better picture than a 60 Hz TV when the SOURCE video is only 60 frames per second.

The 60 FPS source is not always perfectly in sync with the 60Hz vertical refresh of the display. This issue can be resolved either with vertical synchronization, or by increasing the vertical refresh frequency and interpolating frames.

 

[Jeff7181]

I'd be much more impressed with a TV that "adjusts its refresh rate to match the video source" than one that's capable of 240 Hz. Where can I get one of those TV's?

 

[EarthwormJim]

I'd still like to know how a 120 Hz (or 240 for that matter) TV can display a better picture than a 60 Hz TV when the SOURCE video is only 60 frames per second.

It probably won't. It can help make syncing appear smoother though if your source is 24hz.

 

[disappoint]

I'd be much more impressed with a TV that "adjusts its refresh rate to match the video source" than one that's capable of 240 Hz. Where can I get one of those TV's?

You wouldn't be. You might think so now, but if you saw the 2 side by side showing the same fast movement you'd see the difference would be obvious. By the 2 I mean a 240hz display and a 60hz display, both with 60hz input rate and fast motion displayed.

It's not just about syncing although that is part of it.

The real problem is that with fast motion, there aren't enough frames per second in a 60hz refresh rate to make the animation seem smooth. We're talking about very fast motion here though, not Casablanca on DVD.

Consider a ball moving from one side of your screen to the other in much less than a second. The lower the refresh rate, the more "jumpy" the animation will be. At a low refresh rate, you may see the ball on one side of the screen and by the next frame, it will be on the other side of the screen already, not exactly a smooth transition.

It is a concept more easily seen than conceptualized, so I'm not sure my explanation is adequate. I guess you'll have to just see fast movement at your local store on a 120 or 240hz screen and the same motion on a 60hz screen to see if you can see the difference.

Also when displays go 3D consider that the refresh rate is cut in half, as half the frames go to one eye and half to the other, if using the shutter glasses technique for 3D and not the polarized lens technique (or some other). Then 120hz will be a necessity.

 

[toyota]

well it doesnt even take very fast movement to be noticeable. all you have to do is watch any of the demos that compare 60 to 120Hz. I watched on my parents 42inch and there was no way you could go back to 60 after seeing 120.

 

[Borealis7]

i'm still waiting for a 24" 120Hz LCD panel to be released. i've read reviews of some 20inchers over at XBitLabs, but my next monitor will not be less than 24".

 

[toyota]

i'm still waiting for a 24" 120Hz LCD panel to be released. i've read reviews of some 20inchers over at XBitLabs, but my next monitor will not be less than 24".

xbit tested 22inch 1680x1050 monitors and I have not even heard of 20inch 120Hz monitors. also there are already at least two 24 inch 120Hz monitors on the market for months now.

http://3dvision-blog.com/acer-is-preparing-a-24-inch-120hz-full-hd-gaming-monitor/

http://3dvision-blog.com/24-viewsonic-v3d241wm-led-is-a-120hz-display-with-led-backlight/

 

[Sylvanas]

well it doesnt even take very fast movement to be noticeable. all you have to do is watch any of the demos that compare 60 to 120Hz. I watched on my parents 42inch and there was no way you could go back to 60 after seeing 120.

This. I've just spent a month looking for and researching the best 42inch for our house here and there is no doubt whatsoever of the benefits of 120hz over previous models for fluidity- you have to see them side by side to see the comparison. I am still waiting for 120hz monitors to catch on but when they do it'll be time for another upgrade.

 

[Modelworks]

This. I've just spent a month looking for and researching the best 42inch for our house here and there is no doubt whatsoever of the benefits of 120hz over previous models for fluidity- you have to see them side by side to see the comparison. I am still waiting for 120hz monitors to catch on but when they do it'll be time for another upgrade.

I really really despise the term hertz used with lcd monitors, it is very misleading. 120hz doesn't mean that it IS redrawing the screen every 1/120th of a second, it only means that it divides one second into 120 slices and if there is new data during that time slice it updates it. 30fps content is going to look the same on 60hz 120hz 240hz or whatever.

With CRT 120hz meant the screen was being redrawn 120 times a second, with LCD the controller does not update the screen until a pixel changes. In a lcd if you display a static image like a photo the image is never refreshed so refresh rate is zero.

 

[Modelworks]

You wouldn't be. You might think so now, but if you saw the 2 side by side showing the same fast movement you'd see the difference would be obvious. By the 2 I mean a 240hz display and a 60hz display, both with 60hz input rate and fast motion displayed.

It's not just about syncing although that is part of it.

The real problem is that with fast motion, there aren't enough frames per second in a 60hz refresh rate to make the animation seem smooth. We're talking about very fast motion here though, not Casablanca on DVD.

If they don't look the same and the source is 30fps then there is something wrong with the way the displays are processing the signal.

It is all about syncing. The two displays have to change the picture so that 1 second = 30 frames or it wouldn't look right. The content is not interlaced so they have to display a full frame, here 60, 120, 240, 360hz gets you no advantage. LCD only redraw the screen when something changes the rest of the time they are doing nothing.

Fast motion doesn't matter , there is still 30 frames for that one second and they can't be shown any faster regardless of content. Some controllers take those 30fps and interpolate new frames though to make it seem smoother, some people like this effect some don't.

Consider a ball moving from one side of your screen to the other in much less than a second. The lower the refresh rate, the more "jumpy" the animation will be. At a low refresh rate, you may see the ball on one side of the screen and by the next frame, it will be on the other side of the screen already, not exactly a smooth transition.

As long as the image is updated at the same frame rate as the animation, refresh rate doesn't matter. For it to seem smoother on a 120hz or 240hz display , that display would have to create more frames by interpolating two frames. For the animation example you use to appear jumpy the display would have to be updating frames slower than the animations frame rate.

 

[Jeff7181]

You wouldn't be. You might think so now, but if you saw the 2 side by side showing the same fast movement you'd see the difference would be obvious. By the 2 I mean a 240hz display and a 60hz display, both with 60hz input rate and fast motion displayed.

It's not just about syncing although that is part of it.

The real problem is that with fast motion, there aren't enough frames per second in a 60hz refresh rate to make the animation seem smooth. We're talking about very fast motion here though, not Casablanca on DVD.

Consider a ball moving from one side of your screen to the other in much less than a second. The lower the refresh rate, the more "jumpy" the animation will be. At a low refresh rate, you may see the ball on one side of the screen and by the next frame, it will be on the other side of the screen already, not exactly a smooth transition.

It is a concept more easily seen than conceptualized, so I'm not sure my explanation is adequate. I guess you'll have to just see fast movement at your local store on a 120 or 240hz screen and the same motion on a 60hz screen to see if you can see the difference.

Also when displays go 3D consider that the refresh rate is cut in half, as half the frames go to one eye and half to the other, if using the shutter glasses technique for 3D and not the polarized lens technique (or some other). Then 120hz will be a necessity.

Don't you see the problem? 60 Hz = 60 frames per second. If the source video is 60 fps at 120 Hz you're just showing each frame twice... at 240 Hz you're showing each frame four times. It cannot be any more smooth if you're just showing the same frame four times in a row... changing the rate at which frames can be redrawn doesn't add information to the source video. If the source video isn't smooth at 60 frames per second, it's not going to get any more smooth if you show the same frames more than once... the data simply isn't there.

 

[Ben90]

Jeff7181.

The 120/240hz T.Vs use interpolation.

 

[disappoint]

If the source video isn't smooth at 60 frames per second, it's not going to get any more smooth if you show the same frames more than once... the data simply isn't there.

Of course not, which is why it is NOT showing the same frame multiple times. The frames in between are interpolated.

By interpolated we mean the frames are in a sense averaged. So if you have a ball on the left side in one frame, and the right side in the next frame, the interpolated frame in between will show a ball in between the 2 balls. (one ball but in seperate frames)

so visually we see: without interpolation:
o..... o
now with interpolation for example:
o o o o

Ignore the dots they are only there for spacing purposes, as spaces are ignored by this forum software.

It is important to note that in order to do interpolation, you must know the end result in advance. In order to know that, some frames must be delayed and stored in memory to do the interpolation. Therefore the display will lag behind the source. Terrible for FPS (1st person shooter not frames per second) or fast paced video games which is why a 120hz TV is NOT going to make a good gaming monitor. You really want REAL 120hz PC monitor for fast paced FPS (shooter games) By real I mean 120hz signal displayed as 120hz with very low lag. NOT 60 hz signal and 120 or 240hz display, as it must be lagging to interpolate those frames in between.

So in other words it must see at least a frame ahead before it can display the last frame and the interpolated ones in between.

Granted a few milliseconds of lag won't completely ruin your gaming experience, but it isn't ideal.

 

[Jeff7181]

I see... well that makes sense why they're desirable then.

 

[EnzoLT]

wow, i learned a lot from this thread. thank you for those that contributed.