Re: Απάντηση: Re: LCD vs. Plasma TVs
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LCD ... or ... Plasma
-Originally Posted by andrewfee-
Neither technology is better - in some situations, an LCD will be more suitable and in others, a Plasma. Under ideal conditions, right now I would say that Plasma will look better though.
Black Level
When viewing in a dark room, Plasmas have the best black levels (the new Pioneers in particular) though LCD is rapidly catching up, and the new LED backlit Samsungs coming in the next month or two will apparently have better black levels than even the 8G Pios. (I'll be trying to get hold of one to see how they are) Blacks on Plasmas are still visibly grey though, when compared with CRT in a dark room. (but if you set up a CRT to show the same level of shadow detail as the Plasma, the difference is far smaller)
Conversely, in a bright room, the LCD will have better blacks, and a better picture overall, as they reject ambient light much better with their matte screens. Plasmas are starting to catch up here, with some of the newer models having better anti-reflective filters (and Pioneer eliminated an extra layer from the front of the screen, which helps reduce this further) but the image still washes out, and can suffer from reflections in a bright room.
Due to this, LCDs will tend to look much better in most shop environments, but may not look as good as a Plasma in a home environment.
Contrast Ratio
This is where things get a little more complicated. While most people automatically assume a high contrast ratio means that blacks are going to be very good, or that the image will be very bright, it's trickier than that. Contrast ratio is the relationship between light and dark areas on the screen. When calibrated to a set target for whites (around 30 foot-lamberts for viewing in a darkroom) plasmas tend to have a higher on-off contrast ratio than LCDs. This means that blacks tend to be darker, so a full black screen will look darker on a plasma than an LCD.
LCDs often have a higher ANSI contrast ratio than Plasmas though. ANSI contrast is measured with a black/white checkerboard pattern on the screen, and due to the way Plasmas work, having full white and full black on the screen at the same time tends to reduce the contrast, whereas with LCD, the contrast ratio tends to be far closer to the on/off ratio. This means that, in high contrast scenes (such as bright outdoor settings, or bright games etc) the LCD can actually look better.
Newer Plasmas, particularly Pioneer with their "Deep Waffle Rib" cell structure, are doing a lot better with this test than they used to though.
Ideally, a display will have both a high ANSI contrast ratio and On/Off contrast ratio, but on/off tends to be more important if you're watching in a dark room, as dark scenes will look "washed out" otherwise.
Motion Handling
The way Plasma and LCD handle motion is also quite different. Plasma tends to keep the edges of moving objects sharper, but they can suffer from long trails behind them. Due to the way the phosphors used respond red/green/blue trail at a different rate from each other, which can leave coloured trails on the screen. It seems that most people can't see these (or at least don't notice until it's pointed out to them) but if you are susceptible to this problem, anything bright on-screen will suffer from green/blue flashes, and movement will often look like the colours are splitting up. Here's an example from one of the very latest plasmas on the market - look at how the tree in the middle has split into three sections - part is blue, the middle is green, and there is a green/yellow trail behind it, and this wasn't particularly fast movement:
http://sr-388.net/images/misc/tv/DSCF6223.jpg
(note: the camera had a shutter speed of 1/60, to capture one refresh - that's what I see when watching a Plasma)
LCDs handle motion quite differently. With LCD, even with objects moving at slow speeds the edges will soften, giving things a slight "out of focus" look. You'll notice that if you're playing a game (one without motion blur of course) when you stop moving, the image suddenly gets a lot sharper. While you still get some trailing when a dark object moves over a dark background, other than a rare instance like that, trailing tends to show far less than Plasmas, and when it does, it tends to keep the colour the same rather than splitting up.
100/120Hz LCDs are now claiming to "fix" LCD motion handling, but it really doesn't, and in some situations can make things worse. These LCDs work by creating an image in-between two frames by estimating what's happening. This can certainly improve sharpness with some things - the ticker-tapes that you see on news channels are a great example, and the difference is quite noticeable. The problem is that it's all estimation, and some implementations of this are prone to adding artefacts into the image.
With 60fps games (like Forza 2) this interpolation actually tends to add blur to the game where there might not have been any before. If you're buying a set with 100/120Hz, you need to make sure it's optional.
Colour Reproduction
This is another area where LCD is playing catch-up. Plasma tends to look much more natural (especially on out of the box settings) due to it being phosphor based like CRTs, with the gamut (range of colours it reproduces) more closely matching broadcast standards.
LCDs are getting better in some ways, and worse in others. LCDs were very poor initially, but they've been improving dramatically in recent years. The problem is that while they have been improving some things, in other aspects the reproduction has actually got worse. Most LCDs are now using wide colour gamut technology, which will give you deep, vivid and bright colour reproduction... but it's totally inaccurate. Newer wide gamut displays (such as Samsung's latest) are now limiting the gamut to broadcast standards, but the colour still isn't quite right yet.
LCDs also tend to do badly for saturation in dark areas. Due to the way that LCD works, you have a backlight that is always on at a fixed level, so to create black, or darker colours each pixel has to act like a "shutter" to cover it up. This is also one of the reasons blacks tend to be worse on LCD than Plasma - plasma works by creating light from each pixel, whereas LCD works by trying to block light with each pixel. With Plasma you just tell the set to create less light, whereas LCD is trying its best to block it out, which seems to be a harder thing to do. As a result, colours in dark scenes often look very muted, often making the image look very flat on an LCD.
Plasmas on the other-hand do a great job bringing out colour in dark scenes, even better than a CRT. (though possibly too well) The quality of these photos isn't great, but here's Bioshock running on a CRT compared to a Plasma. (using a VGA splitter)
CRT:
http://sr-388.net/images/gaming/360/...k/DSCF6482.jpg
Plasma:
http://sr-388.net/images/gaming/360/...k/DSCF6488.jpg
As you can see, the brighter areas of the image look very similar - the reds/oranges look roughly the same saturation, though they are a slightly different hue. If you look at the dark wall on the right though, you'll see that the plasma has brought out a lot more colour in it.
The other thing is that, compared to a CRT, the Plasma is pixel-based, which means that the colours tend to be "purer" as there is a barrier between each pixel. As a result, the yellows in the lights look a lot more yellow than they do on the CRT, which have picked up some of the surrounding red.
If you open the images in tabs in your browser and switch between them, you'll also notice that the CRT "leaks" more light around the bright areas in the picture, lowering the contrast around the bright sections, as it has a lower ANSI contrast than the Plasma does. (look at the light at the top, for example - you'll see there's an extra glow below it on the CRT)
If I had an LCD here, I'd have compared that with it as well, and you would probably see that the darker sections, such as the wall, would have a lot less colour in them, and the bright sections might actually end up having more.
Resolution
While there are one or two 1080p Plasmas showing up on the market now they're very expensive compared to 1080p LCDs which you can get for about £1000 now. Resolution matters for a couple of reasons - it affects how sharp an image you can get, how close you can sit, and what you can use it for. 1366x768 is too low a resolution to use as a monitor at these sizes, in my opinion. (37" +)
With a 50" Plasma, assuming it is not a 1080p model (as so few exist) you will have to sit at least 12ft back from the screen to avoid being able to see the pixel structure, and PWM noise. (the way the plasma draws its image) For a true "cinematic" experience, you should be sitting around 6ft from a screen this size, going by THX's recommended 36º viewing angle, which is only really possible with a 1080p display. Most people probably won't want to be sitting that close to a TV that size anyway, but it rules out the majority of plasmas available if you do.
The other thing to consider is that while LCDs tend to have a higher resolution with static images, due to the way they handle motion, the resolution drops off dramatically when things start moving. It's not going to affect you perceiving the pixel structure, but while the Plasma is lower resolution with still images, the image tends to actually be higher resolution when things are moving. (sharper, basically)
Past about 12ft from a 50" screen, your eyes won't really be able to tell the difference between a 1080p and a "720p" screen, so that's something else you should consider if you don't plan on sitting any close than that.
Due to their lower resolution, Plasmas tend to handle standard definition content better than 1080p LCDs though.
Viewing Angle, Uniformity
This is an area where Plasma is significantly ahead of LCD. With the exception of a couple of models (Pioneer's 42" 7th Generation, and Samsung's latest) plasmas tend to have a very uniform screen. LCDs on the other hand tend to suffer from "clouding" which means that the screen is not very uniform at all, with large patches that are lighter or darker than the rest. This is only really noticeable in a dark room, but actually seems to be getting more and more frequent, particularly with Samsung/Sony displays and larger sizes.
Viewing angles aren't even a contest. Even the best LCDs tend to wash out the image after about 45º or so, whereas Plasmas have roughly 170º before you really notice anything. Again, Pioneers are ahead of the competition here - most/all other manufacturers have at least two layers to their screen, which means that you will get a slight double-image at wide viewing angles. Pioneer only use one layer though, which avoids this completely. The latest Pioneers do have a new screen coating which, while it rejects a lot more ambient light than previous models, does darken the image slightly if you're above the screen. (though that's not likely to happen really)
Noise / Heat
Another thing you might have to consider is the amount of noise/heat a display puts out. In general, LCDs are a lot quieter and cooler in operation than Plasmas from my experience. With the backlight up full, most LCDs are nearly silent. When you start to turn it down, many sets will buzz slightly, but it's a constant noise. The Sony LCDs I have owned in the past have been completely silent regardless of the backlight setting though.
Plasmas on the other hand, have to deal with a lot of high voltages, and as a result, they all buzz. In particular, the brighter the image is, the louder it'll buzz, and there's really nothing that can be done about it. It's not too loud, but as it's not at a constant level, it's a lot harder to "tune out" than an LCD.
They also put out a lot more heat. Most Plasmas are now passively cooled (up until the last year or so, most of them had a cooling fan) and will heat up a small room a lot more than similar sized LCD. (I've recently had a 52" Samsung LCD in here, which was fine, but with the 50" Pioneer I currently have, I sometimes have to leave my door open to let things cool down.
So, for brighter environments, for people that want to sit up really close to their TV (and/or use it as a monitor) or for people that are able to see the phosphor lag on Plasmas (such as myself) LCDs are going to be the better technology.
In a dark room, for people looking to get the most natural/CRT-like image, or where viewing angle is important, Plasmas are probably the better choice.
