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Panel Technologies explained

Between pouring over reviews, and seeing displays in-person, I think I now know pretty much everything there is to know about LCDs (I hope I don't have to eat those words ).  Anyway, from my research, I think I can make the following generalizations about the various panel technologies used in today's displays.  Of course, I'm NOT an expert, so I can't say with certainty, that the following generalizations are correct.  But I strongly suspect that they are.

First off, going by the manufacturers specifications, even the cheapest TN panels should, theoretically, be awesome.  They're not.  My best advice is to completely ignore the spec sheets, as most of the information therein is a blatant lie.  In fact, the cheap TN panel manufacturers tend to stretch the truth to the point where their panels actually "outperform" the highest quality H-IPS panels in areas like contrast ratio and response time.  TN viewing angles are often quoted at around 170˚ (it's more like 10˚).  The false advertising is so bad, I highly doubt that it could withstand legal scrutiny.  Nevertheless, until the issue is settled in court, bad spec sheets are just a fact of life --all we can do is ignore them.  Here's a quick overview of the various panel types.

TN: Utter garbage.  The 6-bit nature of these panels leads to poor color rendition, severe color banding, severe compression of darks and lights, and noticeable color shift at +/- 5˚, particularly in the vertical direction.  If you display a solid orange on a 24" TN, the result is a gradient effect --the top will look red, the middle will look orange, and the bottom will look yellow.  That's looking head-on; off-axis color shifting is catastrophic.  Applying basic geometry, this effect can be minimized by using a smaller panel, or increasing viewing distance to around 10 feet, or so.  Newer TN panels have achieved respectable black levels, but only in the middle of the screen (because of the aforementioned viewing angle issues).  Response times were once a TN strong point, but other technologies have caught up, in this regard.  "Input lag" is insignificant for most, if not all, TN panels. 

Input Lag is likely an unfamiliar term to most, so I'll define it now.  Basically, every monitor contains circuitry that processes the input data it receives, before finally sending it to the LCD matrix.  Input lag measures how long that processing takes.  It's completely different than response time.  One way to think about it is like this: Input lag is the time it takes for incoming graphics data to begin to affect the pixels of the LCD.  Response time measures how long it takes an affected pixel to reach its desired state.

Despite the severe image quality issues, you'd think that TN-based displays would be the cheapest --and for the most part, you'd be right.  Recently, however, manufacturers have begun putting TN panels in aesthetically pleasing enclosures, and selling them for PVA prices.  The Samsung "Touch of Color" series is, perhaps, the best example of this.  Don't be fooled.

MVA: This is a major step up from TN.  8-bit, much improved color rendition.  Viewing angles are good to about 50˚; beyond that, color is lost gracefully, and could be considered "viewable" right up to 178˚.  Unlike TN, VA screens looks much more uniform when viewed head-on (still not perfect, however).  Response times are good, and input lag is generally insignificant.  Black levels are not MVA's strong suit, and like all *VA panels, there is some loss of dark detail (but nothing like TN).  Best of all, these panels can be found at TN prices, if you know where to look.

PVA: A notch above MVA.  PVA monitors --the Dell 2407FPW-WC being among the best-- are just another variation of *VA technology.  Viewing angles are a little better.  Blacks are the among the deepest you'll ever see, although there is some loss of detail with lower tones.  Like MVA, the viewing angles are wide enough to allow the screen to look mostly uniform when viewed head on (again, not perfect, but still considerably better than TN).  The one issue with PVA is input lag.  In the case of the Dell 2408WFP, the amount of lag is enough to affect gameplay, especially first person shooters.  Some PVA's are better than others, in this regard (the 2408WFP being the worst).

S-IPS: We're almost there!  With S-IPS, viewing angles are spot-on up to 120˚ or so, and nearly perfect right up to 178˚.  So, screen uniformity is flawless, when viewed head-on, and almost perfect, otherwise.  An A-TW polarizer can be incorporated to make viewing angles perfect to 178˚ (just like CRT).  Color rendition is a level above PVA --flawless, with improved dark detail.  Black level is nearly as good as PVA.  Input lag is generally not an issue with S-IPS, though it is in some models.  The 24" iMac is rumored as using an S-IPS panel.

H-IPS: Cream of the crop.  Nearly perfect viewing angles, which can be made absolutely perfect with the addition of an A-TW polarizer.  Perfect color uniformity, perfect color rendition with flawless bright/dark detail.  Black levels are on par with the best PVA's.  I would call these panels CRT-worthy.

Last edited by Mr. T (2009-08-02 1:26 am)

Bat wrote:

Mark & I want 10-bit/channel panels, min, and factory calibration across multiple colorspaces, settable from the display, like this one - out for some time now, nearly a year I think. $3,500 at launch- and ATi, if not NV (can't say), has had a full 10 bit/ch video pipeline end to end for a couple of years now. If your source has it, it can be rendered.

The exact model seems to be the LP2480xz.  I can't find any "objective" reviews, but "subjectively," it looks ahead the pack in terms of image quality. Still, without more objective tests (particularly with respect to input lag) I'm hesitant to conclude that this is the best "all-round" display --though, most likely, it is.

At the affordable end of things, AT opines TNs aren't nearly that bad, or needn't be as other elements improve, like backlighting.

At the lower end of the spectrum, we have the new SP2208WFP. This is a 22" LCD that looks like the 2707WFP's younger brother. While it has all of the attractive styling, however, it does not sport the same feature set. Specifically, it lacks the ability to rotate into portrait mode, and it includes HDMI, DVI, and VGA video inputs. Since this is a display built more for the home market, it does add an integrated webcam to offset the lack of other amenities. It also has a TN panel, just like every other 22" LCD we've seen. This one is rated at 2ms GTG response times and 2000:1 contrast ratio; it comes with 300 nit, 92% color gamut CCFL backlighting - all good specs. We've been hard on TN panels, and we still prefer S-PVA and S-IPS, but the latest TN panels do look quite good. MSRP is $319 and the SP2208WFP is now available; there's currently an instant rebate that brings the pre-tax price down to $284. If you prefer the styling of the 2407WFP as opposed to the 2707WFP, Dell also offers an UltraSharp 2208WFP that includes height adjustment. MSRP is $339 on that model, but the instant rebate is larger bringing the current price to $275.

Since that's from 1/10/08, the price situation at least must've improved, and better models perhaps come along.

AT is one of the better review sites, so their comment on this is certainly promising (It's still not a review, though).  However, this is a 22" 16:9 monitor, as opposed to a 24" 16:10, so the 22" is substantially shorter in height.  The shorter height will reduce the amount of vertical color shift you get when viewing the monitor head-on (I call this the "gradient effect," above).  On my 9" AspireOne, the gradient effect is far less noticeable than on larger screens; just below the threshold of chinese water torture.    I found this video which clearly demonstrates this effect in larger monitors ViewSonic VX2835wm

Then there's still the matter of 6-Bit.  You can pick your poison with regard to coping mechanisms: FRC, banding, or dithering.  I prefer banding myself, as FRC gives me headaches, and dithering looks ugly, imo.

All things considered, there really is no reason to bother with TN --not when you can get a 24" MVA panel for $240 at WalMart.  IMO, while TN's are becoming more expensive, they're not getting that much better.  Soyo makes an uber-cheap 24" PVA panel, but increasingly these have been shipping with TN's, so it's a bit of a gamble as to what you'll get.

Mr. T wrote:

Bat wrote:

Mark & I want 10-bit/channel panels, min, and factory calibration across multiple colorspaces, settable from the display, like this one - out for some time now, nearly a year I think. $3,500 at launch- and ATi, if not NV (can't say), has had a full 10 bit/ch video pipeline end to end for a couple of years now. If your source has it, it can be rendered.

The exact model seems to be the LP2480xz.  I can't find any "objective" reviews, but "subjectively," it looks ahead the pack in terms of image quality. Still, without more objective tests (particularly with respect to input lag) I'm hesitant to conclude that this is the best "all-round" display --though, most likely, it is... AT is one of the better review sites, so their comment on this is certainly promising (It's still not a review, though).

Neither is AT's quick look-see (from a trade show article, IIRC), but Anand Himself wrote up some brief impressions. I linked the page here more than once... maybe I'll have time to look it up again. If one of those landed in my lap, tho, I'd likely use it and not look back. I hate banding, love color depth. Can't wait to try 10bit/ch rendering with my 19" Diamondtron CRT from '04, still working. Carmack once mentioned CRTs could do the equivalent of 36-38 bit color depth. Even in games, with 24 bit color art assets, you'll likely have some that a wealth of blended effects that can benefit. I ♥ bandwidth and floating-point color accuracy.

However, this is a 22" 16:9 monitor, as opposed to a 24" 16:10, so the 22" is substantially shorter in height.

The display industry is pushing 16/9 ratios across the board, so they can standardize panel glass sizes with HDTVs, etc. I don't like it, but it seems to be coming.

Why yes, yes I am waiting for 10-bit displays.  HP is on the right path.  I'd like NEC to take note.  I'll have to check the model numbers, but we bought some NEC 24" displays to travel with our dual MacPro rack and they are a hell of a lot better than I thought they would be and the price was "really right" at around $500 per monitor.

-mark

I've only heard good things about Apple displays. I've also heard that they're better than Dells, even if they use "the same" LCD panel.

ukimalefu wrote:

I've only heard good things about Apple displays. I've also heard that they're better than Dells, even if they use "the same" LCD panel.

In past years, they've been pretty much the same; partisan perspectives aside.  Sadly, that's no longer the case.  Apple's 24" Cinema Display is rumored as using the higher-quality IPS panels, while Dell's 2408fpw is using the cheaper PVA's.  Worse yet, the Dell suffers from a significant amount of input lag, which is problematic for gamers.  Image quality aside, I think Apple's shooting themselves in the foot by going exclusively DisplayPort, and not offering a matte version.

Unread as yet, but looks interesting.

New C-PVA Solutions: Samsung SyncMaster F2080 and F2380
[08/19/09 | Monitors]
According to Samsung, C-PVA matrix is only 10% more expensive than TN-matrixes that have taken over the market these days. However, it is way better in terms of viewing angles and overall image quality.

http://www.xbitlabs.com/articles/monito … f2380.html

Radeon 4870 + 30" Apple Display.

I cannot find fault with it.

Radeon 5870 + 3 30" displays- oh, wait, it's not out yet.

But it apparently can drive 3 displays.

Mr. T wrote:

The LP2475w is back down to $373.99. 

I called up, and got a price adjustment.  They said it'll take 1-2 days to process the $26 refund.  We'll see...  If there's a problem, I still have the rep's name and extension.  Not that I suspect dishonesty, but sometimes things get tied up in red tape.  However, I know other people who have ordered from them (MacMall, actually) without issue, so I feel pretty confident.

But anyway: H-IPS for $374.  That's the top-tier panel tech for less than some TN's.

I can’t find that panel for less than $500 anymore.

I wish I had known the 374 was a sale price

pirloui wrote:

I'm in the marked for a new display, I'm on very tight budget, like pixels and am not too sensitive to colors.
So I thought to get a 21.5" 1920x1080 or a 24" 1920x1200 TN, until this one popped up:
Dell has the 2209WA 22" 1680x1050 e-IPS for 206us$ here in hong kong.
That's the same price as a 24" TN. The 21.5"s has most pixels for the price, at 140us$.

It's terribely frustrating because it's clearly a good price/quality ratio, however a 1680x1050 resolution belongs in a 20" screen, and I really don't like big pixels.
The 21.5" are a pretty good deal, but the 16:9 ratio isn't great for work. They do however have more vertical pixels than the Dell IPS.

argh. Any opinions?

edit: There is also the upcoming LG W2220P which is very interesting 22" 1920x1200 e-IPS for 240€ launch. However it's not out yet and it prie will need to drop.

I'm camping with my powerbook as I have no screen at all for my main computer (after moving)

That's a tough call.  It really depends on how much you're bothered by TN color shift and banding.  If you're even slightly OCD, then do yourself a favor and get the Dell IPS.  Otherwise, the TN does give you more pixels for the money.

Video production is the big reason for > than 8bit per color monitors.  Banding is just horrific using the DV codec; and now with the new ProRes 4:4:4:4 it is even more important for a high bit depth monitor.  Broadcast standard codecs are 10bit video and you can visibly see banding on 8bit/color monitors.  What makes it weird is that video is YUV (Y-Yr-Yb) and LCD technology is RGB, so there is some conversion going on as well.

-mark