Is it really more difficult making a display with good Black Level?

[John Holmes]

In this day and age, there are some really great looking displays for entry and middle ground purchases alike. No doubt, one can get a lot for the buck.

So how can so many manufactures have the talent to make any bright scene look fantastic yet, one has to pay more to get equally good blacks? This can't really be a cost thing... can it?

[Chris D]

Good question. Jason's pretty smart about displays, maybe he or someone else could answer.

[Kevin P]

LCDs are inherently limited in terms of ability to do blacks, since they require an external light source (backlight or projection bulb) and their dynamic range is finite. And most/all of the cheaper displays are LCD.

When you get into the higher-end displays like LED-backlit LCD and plasma, better blacks are possible with these technologies but they also cost more.

Making a display bright is easy. Making it accurate with a wide dynamic range of brightness (including black) is not as easy. Just like in audio, making music loud is easy (just check out any mainstream release nowadays), making it sound good.... well.... :roll:

[John Holmes]

Making a display bright is easy. Making it accurate with a wide dynamic range of brightness (including black) is not as easy. Just like in audio, making music loud is easy (just check out any mainstream release nowadays), making it sound good.... well....

This hits the nail of my question. IMO many displays across the various technologies look accurate or close to. Of course I'm speaking after at least a minimum user setting adjustment with a setup disc. Better even ISF.

And I understand the analogy to today's music... agreed. But even with today's music, a redbook CD can be made to sound stellar for the same or little cost difference. Every display in my home is entry level. I have an 20" LCD monitor for the PC. A 32" Plasma in the bedroom and a DLP projector in my theater. They all look good to great in brighter scenes. And they all suck in the darker ones. Though some not as bad as others. But they all have enough noise and color degradation to make one take notice.

My projector has by far the cleanest blacks of the three, followed by the Plasma then LCD. I fully understand that in my case every display is entry level. But what I don't get, if cost is the true factor as to why black level gets the short end of the stick, how does adding every app known to man, Wi-Fi and or ethernet, 3-D, etcetera save money? Surely getting better blacks is cheaper.

[Kevin P]

Another factor in getting good black detail is the resolution, or bit depth, of the pixels. If the display uses 8 bits per pixel, that allows 256 levels per primary color, or 16 million possible combinations. Blacks comprise of just the first few of those levels, so there aren't as many bits available to render accurate blacks.

Now I don't know what the actual bits-per-pixel (coming out of the DSP and into the display panel) of a modern display is, but I would guess that the effective BPP of a cheap display is lower than that of a high-end display. This would affect black detail.

[JonMarsh]

+:T to Kevin. The thing is, they know how to do this with LCD's- but IPS panels are required for the best color fidelity on and off axis, and good static contrast ratio, but IPS panel construction is considered too expensive for the cost sensitive TV market. As a result, in flat panels, it seems to be plasma's that offer the best fidelity these days, as long as you don't need a light cannon for daylight viewing. If you do need that light cannon, then you'll have to give up a bit in performance off axis (no big deal for some people with fixed viewing positions dead on axis), and less contrast ratio.

BTW, I've yet to see a display with dynamic contrast figures that didn't display some artifacts with real program material under some conditions.

Now, the really funny thing is, the best static contrast ratio's available now seem to be in the DILA reflective chips- were I trying to do high end display in a larger room and didn't have my NEC 10PG CRT projector with 9" tubes, that's what I'd go for. They outperform LCD flat panels for static contrast and have pretty dang good overall performance. from JVC. Sony has similar products in the SXRD. You can get something as cheap as $2798 in the VPLVWPRO1/VPL-HW20 projector from Sony, which has pretty fair static contrast, then uses their IRIS 3 technology to get a dynamic contrast of ~80,000:1. Not as good a static contrast ratio as JVC, but not as expensive, either! It's basically an improved HW15- 1,300 lumens versus 1,000, and 80,000 dynamic contrast versus 60,000- an all new light path design.

[John Holmes]

Okay gentlemen, I understand. Thanks for taking the time to explain it to me. I'm just going to have to up the pot for for my front projector when it comes time to replace it.

[5th element]

It does have to be mentioned I believe, that the eye only has a fairly narrow static contrast ratio too. This is why bright scenes looks great, crank up the brightness and the minimum black level the eye can detect shoots up too.

Of course this is of little importance when the entire picture is dark. The eye having a fantastic dynamic contrast ratio starts to notice that black, is not black any more.

One thing that bares mentioning is colour compression, sometimes software will limit the end points so that the darkest blacks and brightest colour settings won't go above or below a fixed point, say 16-235 on the 8 bit scale. This isn't so noticeable on the bright end of things, but it does make blacks look washed out. So make sure that nothing sneaky is going on somewhere in a media player or graphics card settings.

Panel technology really is abysmal and needs an overhaul. As Jon mentioned you really need to use an IPS panel to get really nice colour accuracy and decent viewing angles. However they come with their own problems, such as panel glow and limited black levels. Panel glow only occurs at some odd angles and has typically been sorted for the majority of applications. But the minimum black depth is still an issue.

An edge lit LED back light wont offer much of a performance gain over a typical affair, although where LEDs can offer a performance gain is in colour rendering as the CRI of an LED can be really high.

Where LEDs can 'shine' quite literally is if an array of them is used for illumination, rather then an edge back-light. This lets the back-light intensity be varied from one section of the panel to the next allowing for a better dynamic contrast ratio regime. The trouble is that getting a uniform back light, without any hotspots is a trouble, as panels tend to be thin and thin diffusers don't work as well as thicker ones. Hence this is more expensive, if used at all? I've read about it as an application, but I can't remember seeing a panel set up like this.

As has been stated, getting a black level is all about blocking out light. As the back-light is on all the time, for a black, black you need to cut out all of the light. VA panels typically excel in this area, but come with their own issues, one known as black crush, and the other known as gamma shift.

Black crush can be a terrible problem on some poorly made screens or poorly conceived setups. Yes you might have a 0.02 black depth, but the detail you can see within that black is rubbish. Ie you can't see any shadow detail. If you then angle the screen slightly, the details start to show up.

Gamma shift occurs because your eyes don't view each pixel with the same viewing angle. Those in the centre of the screen are at 0 degrees whereas those at the edges sit at a larger angle the closer you sit. Due to the nature of VA panels, the uniformity of the screen changes as you view them at different angles and this causes the edges of the screen to have a different colour balance to those at the centre. The issues VA panels tend to come with are alleviated the further away you sit and if you're slightly off centre, so they are used a lot for TVs, but can be an issue on computers, where you typically sit a lot closer to the screen and we haven't even talked about response times either, an area VA panels typically perform quite poorly in.

One other thing to mention is you can have a screen technology capable of a great black level, but due to construction and quality control, you end up with back-light bleed. Where the black-light, literally bleeds around the edges of the panel and creates patches that glow, so another thing that can ruin an otherwise good product.

The answer to all of these evils is OLED, these don't require a back-light, as each pixel is made up of three LEDs. To create a black pixel you turn all three off, boom no light, perfect black. And as there isn't anything 'mechanical' going on inside the pixel, the response time is as fast as the LED can be switched off and on, ergo really fast.

The trouble with OLED is life expectancy and currently the price of manufacture and this isn't something that is offset by mass production, they are currently expensive to make. Of course as the technology matures, prices will tumble and the life expectancy will increase and then we will have our 'perfect' displays, but until then...you pick your choice of compromises.

Typically the best overall option is an IPS panel, these have good viewing angles, good colour reproduction, fast enough response times and a black level that is adequate for everything other then really dark scenes in computer games and movies.

[aud19]

But what I don't get, if cost is the true factor as to why black level gets the short end of the stick, how does adding every app known to man, Wi-Fi and or ethernet, 3-D, etcetera save money? Surely getting better blacks is cheaper.

Most of the technical aspects from your original question have already been covered so I'l do my best to answer this question.

Companies aren't stupid and they know that the more logos and "features" they have listed on their spec sheets the more likely the buyer is to pick their TV over the competition set that lacks them. Basically buyers don't care enough about black levels because there's no "black level logo" on the box.

It's the same with the inflated contrast ratios they spout off on or even throwing that out and quoting "dynamic contrast" (as though it means something). Or with LCD's refresh rates (even though their motion schemes to negate the inherent motion issues with LCD make film look like crap) etc, etc...

OLED is apparently coming down the line in the next few years but hopefully it doesn't run in to the same problem that SED did. Basically that consumers felt what they had was already "good enough" and the high-end market is pretty small and hence it's difficult to break in new tech if it can't be at least SOMEWHAT price competitive with say a 60" LG plasma for $1250.

[impala454]

I have a 24" IPS panel from HP and caught myself watching Avatar on it... by far the nicest looking picture I have seen. Just wish they could give me an 80" version for oh... $500?

[aud19]

Yeah I've got the 27" Dell IPS panel and it's sure pretty but the blacks on my old Hitachi CRT RPTV are better and it still has issues with fast motion like any LCD.

Bright, still stuff looks great though :lol:

[5th element]

Yeah I've got a Dell IPS too. There is a large market for decent quality screens on PCs. After all you've got the cheapo TN panel end of the market, where poor image quality is rampant, but acreage is plentiful. Lots of people buy those and are happy with them, but there are enough people wanting to spend say 2-4x the amount of the TN to get better image quality, otherwise we wouldn't have the Dell IPS Ultrasharp ranges etc. It's up to the the marketing departments to get OLED into a price competitive band and to make it sell. I don't see this being a problem unless something else comes along that is technically superior to OLED. We've already got small OLEDs being used on the consumer scale, therefore the technology wont just fizzle out unless it's superseded. Although what I hope doesn't happen, is some bright spark comes up with a new technology that's 1/2 the price of OLED, but doesn't offer quite the technical prowess and as a result OLED is abandoned for it >.<

[John Holmes]

Thanks, 5th Element and Jason for your contributions.

The info everyone's posted has given me a better understanding of what to look for when in my future displays.