Re: Bit of a Con Really - Follow-up ...

Ah, so that is why they are backlit then?

So they can 'make their own? What a prat. An LCD display IS a color transparency.

Reply to
The Natural Philosopher
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In the case of an LCD display, that is correct. However, I expect his intended meaning was CRTs, Plasmas, OLEDs, proper LEDs, and SEDs, all of which *do* "make their own" ...

Arfa

Reply to
Arfa Daily

Considering the litiginous nature of U.S. society, and some of the consumer product cases that William cited in a thread from a few months ago (Canderel sugar substitute was it ? Something like that anyway) I'm surprised at that. Also, Ramsay and his sausages is probably more of the exception than the rule nowadays in the UK. Since handing over the running of our nation in every way possible to faceless wonders in Brussels, we are so bogged down in legislation about what we can and can't say about products that we can and can't sell in ways that they dictate, I'm sure that someone will jump on this sooner or later to say that unless it's at least 72.65% LEDs, you can't call it a "LED TV" d;~}

I think that I would have to contest your point of "very limited control". All of the (recent) half-way decent LCD screens that I have seen to date, have a perfectly adequate contrast ratio. Certainly, the one in my kitchen produces deep enough blacks and bright enough whites to be absolutely fine under the pretty intense flourescent light that I have in there. This is one of the reasons that I question the requirement to extinguish areas of the backlighting in order to 'improve' the rendition of blacks.

With HD now, the resolution of the panels is high, and the speed of them is enough to cope with 100Hz refresh rates

White LEDs do exist in a form that is not RGB based, and in fact is the commonest form of them. They are blue LEDs with a yellow phosphor overlaid. There is a wide variety of 'colours' of white available, including ones that are distinctly bluish, and ones that are yellowish.

Well actually, the one in my kitchen isn't, neither is the one in my daughter's lounge. The new Pan that I saw Friday in my friend's shop, was excellent in that respect, giving an extremely nicely 'balanced' picture. There are aspects of flat panel displays which cause me to like them less than CRTs, but 'general' picture quality in terms of brightness, contrast etc, is not one of them. I think that in general, they've got that one nailed down now.

Arfa

Reply to
Arfa Daily

You're not quite correct there. They do dim with age, and that is actually the way that they are specified for lifetime expectancy. I seem to remember that it is something like 'hours to the 50% point'. The figure drops drastically if they are DC driven rather than pulse driven, and if they are 'abused' with excess current. I have also seen dead LEDs in indicators, bargraph displays, and where they are used as some kind of voltage reference in amplifier output stages.

Arfa

Reply to
Arfa Daily

If you're just watching casually under high ambient lighting, the quality of the blacks is pretty irrelevant. It's when you're doing some serious viewing under subdued lighting that it matters. And this is exactly where ordinary backlit LCD falls over against CRT.

Reply to
Dave Plowman (News)

Dear me. Got out of bed the wrong side today? You do seem to be getting a little impolite lately! Anyway...

Unlike a slide (usually shown with a halogen lamp) or a print (usually shown under whatever ambient light is about) most LCD displays have a backlight specially chosen by the manufacturer to meet some compromise of (good colour, cheap, low power, probably something else I can't think of) when operating with the particular LCD filters in front of them.

A slide has a pretty good match to the colours of the real scene. It has to, because the slide manufacturer didn't make the projector.

There's no such requirement for a display - it's the light emitted by the entire combination of backlight and filters that matters.

OK?

Andy

Reply to
Andy Champ

Granted, but this is a general entertainment device. When does anyone do any 'serious' viewing on a TV set, especially a not-very-special 32" LCD ? These things are designed to have Coronation Street watched on them in normal, averagely lit lounges really. I've seen some of the Sony offerings that are intended as 'serious' home cinema displays, displayed in subdued lighting demo rooms. One that I was particulary impressed by, was in a Sony store in Vegas. That set had standard constant intensity CCFL backlighting, and I don't recall thinking that there was any problem at all with the way it rendered blacks. Have you had a look at one of these LED backlit Sammys yet Dave ? As you are involved with the broadcast business - allbeit on the sound side rather than the vision - I would be interested to know what you make the picture compared to others. Waitrose have them, so I guess John Lewis would as well, as well as the Currys barns, probably.

Arfa

Reply to
Arfa Daily

That's not really right...

The color rendition of a transparency -- or print -- is intended to be "correct" under a specific illuminant, usually one with a continous spectrum, at a specific color temperature.

For the colors in a print or transparency to be "correct" in any absolute sense -- that is, to actually "match" the colors of the original scene -- they would have to have the same spectral characteristics. They rarely do. And they don't have to, if the way the eye is stimulated is close.

Exactly the same thing applies to prints and transparencies. What the eye & brain think they see is all that matters.

Nope. See preceding.

Reply to
William Sommerwerck

Me, for one. Some things I like to watch properly - not just glance at. And it's not so very long ago a 28" CRT was pretty well top of the range. But when I do sit down to watch TV I do it under controlled lighting conditions - and through a good stereo sound system too. I want to see it at its best.

Maybe, but then so was every TV ever made.

No - I'm not in the market for a new TV yet.

All I do know was I worked on an HD TV shoot recently where the monitors were all LCD HD (and Pro ones so I assume state of the art). And on the numerous night scenes the LD was relying totally on his scope to set black level rather than the monitor. Which was displaying various shades of grey where it should have been black. Quite a 'contrast' from the Grade 1 CRT location monitors which were used for SD.

Reply to
Dave Plowman (News)

No it is not!

A transparency is a subtractive process. An lcd is additive.

Each pixel in a film transparency has three filter layers each of which can absorb a colour.

Each pixel on an lcd is made from three different colour subpixels. The subpixels each have a colour filter behind them to make them RGorB.

Reply to
dennis

It's not a bad analogy.

LCD backlights are usually chosen to have a pretty good spectral response.

But then different makes of transparencies give different results...

How about LCD projectors?

Reply to
Dave Plowman (News)

Is anyone making grade one CRT monitors or hi spec CRT's still?...

Reply to
tony sayer

indeed, but you'd have to have a huge mismatch between backlight CCT and displayed image CCT for that problem to occur. A 15,000K backlight with a 5000K display works just fine.

yes that happens with film, but nothing like it happens with an LCD display. What happens is that if your image is far removed from the backlight in terms of CCT, then one of the RGB LCD colour channels operates over part of its potential range, not the full range. So for example on this display the B pixels might never exceed 50% light transmission. It doesnt cause a problem.

of course

NT

Reply to
meow2222

I cant conclude anything, but I know 2 things:

  1. NTSC is widely known as Never The Same Color twice
  2. The PAL system includes measures to counter phase shift causing colour issues, so I can only conclude that the system engineers thought this was a problem with NTSC.

And fwiw, IIUC PAL rendered colours are designed to alternate the error line after line rather than get each line colour correct, so like many such measures it usually solves the problem, but not always.

isnt that just an adjustment thing? And yes, I agree many wont go dim enough, but some do.

NT

Reply to
meow2222

I don't have the time to discuss this at length, but NTSC's unfortunate reverse-acronym was the result of poor studio standards, and is not inherent in the system. PAL incorporated phase alternation to partly compensate for transmission problems (non-linear group delay) in Europe.

Correct. That's why color errors roughly cancelled out, at the expense of loss of satruation.

Reply to
William Sommerwerck

In article , William Sommerwerck scribeth thus

Wasn't something done to either the NTSC transmission spec or the sets that largely alleviated that .. sometime after the original system started?..

Simple PAL and de luxe PAL IIRC but it was a long time ago now;)..

Reply to
tony sayer

No transparency can show a spectral section that isn't in the spectrum of the illuminant.

Which is why monochromatic backlights or projector light sources are not used.

I challenge you to e.g. produce a natural colour with a sodium lamp..no matter how you tweak the color dyes.

Reply to
The Natural Philosopher

Think again.

I've not heard of pixels with respect to film before. Make it up as we go along?

Which amounts to the same thing in practice.

50% on two colors and 0 on another in film = LCD primary.

As far as the eye is concerned. The issue being that the colours in all cases are relatively broad spectrum colours. You cant get monochromatic colour with either system if you want overall balance. You are not mixing pure red, pure blue and pure green any more than you are notching out everything BUT pure magenta pure cyan or pure yellow..

Reply to
The Natural Philosopher

And transparencies are usually used for top quality magazine prints not 'projected onto a screen' anyway.

Reply to
The Natural Philosopher

It is. Multipath effects caused unacceptable phase and color shifts.

NTSC worked fine on cable, but never as a medium for over air transmissin with any HINT of multipath.

PAL incorporated phase alternation to partly compensate for

sorry, that's a factor of ANY RF tranmission where more than one path to teh receiver exists.

? huh?

>
Reply to
The Natural Philosopher

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