LED lcd VS Plasma - which is better?

Plasma is still top dog, LCD is close to color reproduction, but not to the level of Plasmas.

I think you may need to go review the Color Gamut of the new 40" Samsung LED LCD - i don't think a plasma even approaches it's numbers - perhaps an Elite may?

September 6, 2006 Samsung used the backdrop of the IFA show to announced a 40" LCD TV with high powered LED Backlight technology. The new technology has already received the prestigious "Innovation Award" from the EISA (European Image and Sound Association) for its superb features including LED light source,

146% wide colour gamut and industry leading contrast ratio (10,000:1). The new 40" with LED light source realises far richer colour reproduction.

Don't wider than normal color gamuts not matter until there is a format that supports them? For example, I thought setting the color gamut to "wide" on the XBR2s and XBR3s distorted the image because cable, dvd, hddvd, and br don't support wider than the ntsc standards.

LEDs have far superior color purity than any phosphor; they are almost perfectly monochromatic due to quantum emission. Phosphor-based technologies are CRT direct view, CRT rear projection, plasma, and SED.

The image below is excerpted from p.3 of an interesting paper (PDF) by NEC on their LED-backlit LCD2180WG LCD:


Comparing CCFL to phosphor output spectra, we next turn to Colorimetric Characterization of Three Computer Displays (LCD and CRT) (PDF). This valuable paper is one of the only (online) to provide graphic phosphor spectra; the main subject is a comparison of the various characteristics of three displays: an SGI 1600SW LCD, IBM 'prototype' LCD and a Sony GDM-F500 CRT.

Remember, the following graphs are normalized spectra, so look only at the dark dotted line, not the solid, light dotted or light dashed lines.

First, let's look at the red channel:







Both CRT and CCFL emitters do well with good purity. The CCFL emitter is slightly orange compared to phosphor. Phosphor wastes energy with a spurious emission band in the near-infrared.

On to green:







This is where phosphor and CCFL emitters part company. The phosphor emitter shows characteristic awful purity, with a huge hill-shaped emission band whose peak is centered on 'green'. The visible yellow-greenish color of CRT phosphor is due to the slowly-decaying slope to the right, persisting long into the yellow and even including some orange. In contrast, the CCFL emitter maintains a consistently narrow output.

Finally, the blue:







Again the CRT blue is a disaster, only slightly less than its green. CCFL blue has significant broadband emissions in the blue-aqua region, with a sharp band in the aqua. Of the three primaries, CCFL phosphor's color purity is worst for blue, and very good for red and green.

Comparing CRT to CCFL emission spectra, the CRT loses worst in green, not so badly in blue, and produces a significantly deeper and also purer red than CCFL.

Both plasma and Cold Cathode Flurorescent LCD backlights use UV (ultraviolet) excited phosphors to produce light. It might be expected that plasma will have similar output spectra and purity to CCFL, but then again the formulations may be different.

Finally, comparing LED to CRT and CCFL phosphor spectra, LED clearly wins.

Spectral purity is achieved by making the three primary emission lines as narrow as possible, and locating them in the correct three frequencies. This allows colors to be as pure and saturated as possible. So red should have an infinitely thin line between 650-670nm (user preference), green at 550nm and blue at 425-440nm.

Coming from a high end CRT, it's appalling what's suppose to pass for a good contrast ratio these days in flat panel tech. Or good dark scene reproduction, in LCD anyway...

I'd guess Plasma still for overall PQ vs. LCD...

Also LCOS is certainly worth checking out, if rear projection is an option...

I thought I read that these statistics on color gamut were comparing the 146% to an old standard that isn't used anymore? Anyone?

Justin

I suppose you are correct but the gap is fairly narrow.

"Contrast ratio is the most important aspect of screen quality, according to research by the Society of Motion Picture and Television Engineers. Although plasma can produce more contrast than LCD, it does not always do so. Sony's LCD showed better contrast than a 42-inch Hitachi 42HDS69 plasma in the lab. And a plasma's contrast advantage fades away - literally - in bright rooms, where the ambient light overpowers dark tones.

After contrast, color saturation and accuracy are the next most important quality factors. Though plasma panels used to beat LCDs on these measures, the technologies are now about equal." http://www.iht.com/articles/2006/09/.../ptbasic14.php

"I suppose you are correct but the gap is fairly narrow...."

Actually, it's huge. A CRT's contrast ratio (GDM-F520) has been measured as high as 15,000:1. I think the highest LCD I've heard of is 2000:1.

This press release is in line with what I've seen elsewhere:

http://www.digitimes.com/print/a20060928A6032.html

(Referring to real, on/off, contrast, not the "dynamic contrast ratio" that some advertise.)

It was a big deal when the Sony Bravia sets came out, featuring an improved contrast ratio of 1300 to 1 or thereabouts. And it was a noticeable improvement. But what a small fish tank we've been forced to swim in these last few years...

(To their credit, I think Sony tried to keep selling CRTs...)

I totally agree with you. My comment was meant to address the contrast ratio between plasma and LCDs. "I'd guess Plasma still for overall PQ vs. LCD..." If you reread my post you should see that it discusses plasma and LCD. Sorry for the confusion.

Well, the new LED-LCDs from Samsung and JVC have 10K:1 and 12K:1 contrast ratios respectively, so that gap is shrinking fast.

Oh...well, yes, I guess that has become a tighter race...

(I think some plasma manufacturers have made some strides in the contrast department. Panasonic maybe...something about more effectively being able to prevent light bleed through between adjacent cells...)

The contrast ratios those companies are giving you are total BS. Real world contrast ratios are never given in those salesmen contrast numbers.

A "3000" contrast plasma will out perform a 10,000 contrast on many occasion.

Also those contrast numbers are usually a Dynamic measurement. Full on/off isn't as useful as an ANSI contrast ratio... which is a much more accurate representation of what you're seeing on screen.

You're referring to dynamic contrast ratio? (I was referring to real, on/off, contrast ratio, where the gap remains a depressing chasm...)

I think many would say the opposite. LCD is actually superior to CRT in an ANSI test pattern, because of a CRT's internal reflections. It's the on/off or limited overall range where LCD struggles and that makes a huge difference...

(Maybe because so much of programming involves darker scenes and such, where flat panel tech shows its weaknesses. But then you show a bright scene where the flat panel is most likely to shine, but the CRT still looks great too, even with the weaker ANSI contrast...)

I'd put my 3 year-old CRT against most LCD's.

I haven't kept up with the recent improvements to Plasma sets. What are the major drawbacks to a Plasma set? I have heard the sets don't last near as long as LCD's or CRT's. I might be looking for a bigger model a year from now.

True that ANSI contrast is only one measurement of contrast of course. But I am just saying contrast ratios that are measured with both light and dark are more accurate... from flat panel to flat panel mostly.

We all know CRTs have a contrast ratio that is unbeatable in the dark.

Probably. So you mean that when I see 10K:1 on LCD it is different than 10K:1 on plasma? I'm confused.

I believe in the case of LCD, "dynamic contrast" refers to dynamic adjustment of the backlight, but there's only so much one can do with that approach...

Plasma 10K:1? Is that the real deal based on improvements Panasonic made in achieving a better black or what have you...I'm not sure....

You could put your CRT up against most plasma and LCD for SD and black level display.

Although there are many many many plasma vs lcd threads on this forum, the truth is that both technologies are maturing and are enjoyed by their respective owners. Plasma owners bash LCDs and LCD owners bash plasmas. Go figure. LOL! Both technologies have pluses and both have minus. Some are actual, some are perceived. Which is better for you really depends upon your viewing habits, environment, bank account, and most importantly your own eyes!

Display 'life' should not be an issue with either plasma or LCDs. Both technologies are claiming 60,000 plus. Of course only time will tell if these numbers hold.

A contrast ratio is a mostly useless statistic, but manufacturers were (and still are) getting so outrageous with their contrast-ratio claims . . . The more useful numbers are the actual black level and light output numbers. http://www.hometheatermag.com/gearwo...ear/index.html

Contrast ratio when accurate isn't a useless statistic. Its when manufacturers in an attempt to outspec the compitition start making up their own numbers, that we have problems.

Today it really is a useless spec. Each manufacture wants to outdo the other so they create new ways to measure, new methods of reporting, etc. etc. You can not compare one set with another because you do not always know how that sets numbers were achieved.

"A high contrast ratio is a good thing but alone tells you nothing. A display with a 4,000:1 contrast ratio but with a black level of 0.099 ft-L may not look as good in a dark room as a display with a 3,000:1 contrast ratio but a black level of 0.010 ft-L. " http://www.hometheatermag.com/gearwo...ear/index.html

"Unfortunately, we've reached the point of ridiculousness. It has no real-world application. (I never watch all white or all black screens, do you?) And it doesn't account for light leakage across the picture or outside the device. Far worse, however, many manufacturers now use electronic tricks to accentuate contrast ratio by forcing black levels. But that's where this quest for marketing advantage has really become hurtful to true image quality."

"And there is more to contrast ratio than literally meets the eye at any given instant. But leave it to marketers to rip the subtlety out of any positive concept and hammer away until it is nearly meaningless. Alas, that's what is happening with contrast ratio." http://www.svconline.com/mag/avinsta...pted_contrast/

True, comparing contrast number specs between manufacturers isn't terribly useful. But we should make sure not to confuse people that "contrast ratio" is a useless metric. As long as it is measured competently and consistently, contrast ratio numbers are revealing of pq performance. (For instance the contrast ratio measurements from some magazines can be quite useful).

Agree

Perfectly Stated!!!!! It's all in the eye of the beholder.

Contrast ratio's and black levels are not directly related.
A very bright display can have a good contrast ratio but poor black level, where as a display with great black level, that is not very bright, can have a relatively poor contrast ratio.
Black level is THE most important spec, and it is never quoted.

I believe that you made conflicting statements. First, you wrote that contrast ratios and black levels are not directly related. Then, in your following statement you identified a direct relationship between contrast ratios and black levels. "A very bright display can have a good contrast ratio but poor black level, where as a display with great black level, that is not very bright, can have a relatively poor contrast ratio."

The Society of Motion Picture and Television Engineers disagree with your statement on black levels and identify contrast as the MOST important aspect of screen quality. After contrast, color saturation and accuracy are the next most important quality factors. http://www.iht.com/articles/2006/09/.../ptbasic14.php

Black level specs are seldom "quoted" because they are not the most important aspect to picture quality.

BTW I am not speaking about a vendor's reported contrast levels - not sure I believe those - but the actual level you experience when viewing.

Nmlogo,

I think he's talking about absolute blacks. With a bright set, you can have a good contrast ratio but absolute black can still be too light.

The Society's statement about contrast is correct presuming that you also factor in their peak brightness specification. When you do that, then a good contrast ratio would also have good blacks.

At least with regard to computer monitor reviews, sites such as ExtremeTech list black levels in their results. Definitely, one heck of a differentiator if one can get the data...