The good and the bad of HD TVs

[Geo]

Another thing that could be added is many of the flat panel TV's (LCD and Plasmas alike and some super cheap CRTs) tend to use sub-par internal speakers that many people find weak.

There are people buying HD TVs and using the internal speakers? Oh, the horror!

 

[Tahir2]

I use the internal speakers for my Panasonic TH42PX60, only turn on my A/V receiver when I am watching a movie to be honest.

 

[Frank]

I've got a lot more info and corrections coming, but I wanted to give some feedback first.

For me LCD is more like that:

LCD (digital)
Pros:
- Flat and light
- Long lifetime
- Very crisp picture
- Very bright
- Useable as a monitor
- Very easy on the eyes
- High native resolution
Cons:
- Risk of defective pixels
- Risk of panel nonuniformity problems and Mura defects
- Low refresh speed (ghosting)
- Bad scaling (depending on the combination of panel/scaller)
- Low contrast (depending on the quality of panel and electonic drivers)
- Medium luminance
- Medium color representation (depending on the quality of the backlight/panel)
- Automatic aliasing

Good job DiGuru

Thanks. I'll add parts of that.

The contrast is actually not bad with the recent models. Although the manufacturers often claim 1:3000 or more, it's actually more like 1:800. Which is pretty good.

nice writeup, very direct and to the point, would like to see links to actual data, references of reputable nature if you will, but nice writeup overall,...... but i have to take exception to the last part

you don't "need at least" DVI or HDMI for HD TV, HDTV can be delivered to a HDTV via Component cabling just fine, matter of fact, Component can provide the same resolution as HDMI, including 1080p, but there are other limiting factors introduced by a third party such as ICT, while HDMI may be superior on paper, i have yet to see any distinguishable advantage in using HDMi over Component, especially since i always run a separate audio cable, Toslink or Coax to my surround receiver, the only advantage i could see if if i had a A/V Reciever with DD True HD audio and HDMI passthrough, that seems to be the only way to get DD True HD sound, via HDMI

i have a Toshiba 46H84 CRT-RP-HDTV with HDMI and Component and have tested all the available connections possible using a Toshiba SD-5980U Upconverting DVD player, Motorola DCT 6412 III DVR/HD Dual Tuner Comcast box (have had three generations of these over the years), Xbox 360, etc....and have never had a problem getting the TV and any component with HDMI to handshake successfully.....maybe i am just lucky?

Thanks. There is a difference between simple HD TV and HD TV with HDCP. THe latter you need for all the upcoming "true" HD media. I's in the specs, that when you use HDCP protected media and the next device in the chain doesn't support that, it should be restricted to DVD resolution. And the problem is in the protocol. When you want to watch a BlueRay disk, for example, there is a lot of handshaking and other stuff going on in the background between the BR player and the TV, to make sure the content will be correctly descrambled by the monitor. Which requires a digital connection (DVI or HDMI). And it often only works with hardware of the same brand, that all have the latest firmware.

Nice list, DiGuru.

- SCART doesn't necessarily have bad signal quality - RGB over SCART (with a good cable) isn't far away from YUV. (After all, it's a component signal as well...)

Thanks. But while SCART might offer the same quality, if you use good and expensive cables (that use good coax for the RGB signal, for example), it often doesn't. I think that is mostly because it's seen as an old and depreciated standard.

Plasma better contrast than CRTs?

Well, it should. Each pixel has multiple beam emitters build in, is switched (kept active) AFAIK, and it offers a better granularity. But that might depend on the type of display, and how the individual pixels are steered. I'll come back on this.

I'm not entirely sure i'd put ghosting as a negative for LCDs since most brand models (meaning Sony not Soni) from 2003-2004 on dont experiance it. It would have to be a seriously old LCD to ghost an image after the frame has passed. I'm actually quite sure you ment image streaking instead of ghosting, thats also been eliminated on most sets these days.

Ghosting to an LCD is like a fast burn in that dissipates, something like if a logo was displayed in the end of a comcercial then another comercial came up and for a second or two you could still see the outline of the logo in the previous comercial. Streaking is when a frame doesnt update fast enough and leaves a remnants of it seeming to bleed into the picture. Such as if you were moving down a dark hall with lights spaced over head in a video game, and every time you moved it made the lights bleed or streak together making them appear to be linked when they arent. The latter was noticed far more in your fast paced games then the former and the former was one of the first things eliminated as LCDs progressed.

Good point, but I think it's mostly semantics for most people. I'll fix it.

Two other things that arent there are picture quality at wide viewing angles (CRT/Plasma > LCD) and advantages under certain light conditions, such as LCD still displaying a good quality picture in a heavily lit room where as people might see the Plasmas picture obviously superior in a low light room.

Definitely.

Another thing that could be added is many of the flat panel TV's (LCD and Plasmas alike and some super cheap CRTs) tend to use sub-par internal speakers that many people find weak.

Yes, but that would depend on the brand and model, not on the technology. I'll skip this here.

Not true. LCDs at ~42" mark are generally listed between 200-250W typical draw. Plasmas for the same size are 300-400W. Its totally dependant on the brand (Sony specifically seem to be conservative) and the audio features included.

Agreed.


I'll make the update when I know which part I should do next.

 

[Tahir2]

Contrast is a misnomer .. Contrast is black level and CRT's still beat Plasma's for black levels.

 

[Frank]

Btw, if you have a wide and flat screen hooked up to your computer, check out the very nice Monitor Test.

The most interesting thing to me was seeing that the refresh frequencies don't match up, as I clearly see tearing in the test for that. While it is what it should be for that resolution according to the manual (60Hz, many of the lower resolutions need higher refresh frequencies).

 

[RobertR1]

Contrast is a misnomer .. Contrast is black level and CRT's still beat Plasma's for black levels.

The Panny's are getting close. I heard their upcoming models being shown at CES with a 20,000:1 (i know, marketing term) contrast ratio are quite impressive. Only 1.5 more weeks!

 

[MfA]

Well, it should. Each pixel has multiple beam emitters build in, is switched (kept active) AFAIK

That's the problem right there. Fluorescent lighting takes a lot of time and energy to start up, you can't afford to turn it off to achieve true black.

LED backlit LCDs can do true black (if you have the LEDs anyway then driving them individually doesn't really add anything to the cost of the display). Unfortunately the patents for the HDR displays are a big roadblock ... do any of the led backlit TVs have individually driven leds, or do they just switch the brightness of the entire array to boost their theoretical contrast ratios?

 

[Frank]

That's the problem right there. Fluorescent lighting takes a lot of time and energy to start up, you can't afford to turn it off to achieve true black.

Good point. But they can be brighter as well.

LED backlit LCDs can do true black (if you have the LEDs anyway then driving them individually doesn't really add anything to the cost of the display). Unfortunately the patents for the HDR displays are a big roadblock ... do any of the led backlit TVs have individually driven leds, or do they just switch the brightness of the entire array to boost their theoretical contrast ratios?

Changing the intensity of the whole backlight is what the manufacturers call "dynamic contrast". As for using individual leds, you have two problems: the cost of the array, and the color of the leds.

You want white light, but that is hard to create. The closest solution is using a led inside a tiny fluorescent tube. Otherwise, you have to use RGB. And if you use RGB, you have to come up with a mask or refractor that spreads the light, or you should give each subpixel it's own LED. And in that case, it's easier to simply make a LED display.

LEDs are normally created as semiconductors. If you need 3 million of them, and you have to fix all of them individually in place, that makes it even more expensive than simply tiling complete wafers. That's why large LED tv's are about as expensive as a high-performance sports car, while still having a terribly bad resolution. So the best they have come up with so far, is flat rectangles that cover an array of pixels. And those are switched individually.

 

[ShootMyMonkey]

LED backlit LCDs can do true black (if you have the LEDs anyway then driving them individually doesn't really add anything to the cost of the display). Unfortunately the patents for the HDR displays are a big roadblock ... do any of the led backlit TVs have individually driven leds, or do they just switch the brightness of the entire array to boost their theoretical contrast ratios?

The Samsung LED-backlit displays purportedly do individually drive small bunches of LEDs. But the array is much lower resolution than the screen, so they can't really afford to *completely* shut off any of the LED clusters unless there's a really large region of pixels that are totally black.

If you look on Samsung's page about the LE-40M91B, you should see them saying as much. Too bad that display will be long worthless by the time they ever even consider selling it in the US. I believe the Syncmaster XL20, which is very recently or very soon to be available in the US (depending on who you ask) does NOT do any sort of localized brightness variations (and thus has only a 1000:1 constrast) and uses an LED backlight solely for the widened color gamut.

 

[Tahir2]

Contrast is a misnomer .. Contrast is black level and CRT's still beat Plasma's for black levels.

Brain fart on my part, Contrast is brightness and Brightness is... black levels. That's what the AVIA DVD taught me at least.

DiGuru as you know you have had a lot of responses varying in opinion. One of the reasons is that assessing image quality can be a subjective experience and unless it is done in a scientific manner, (i.e. lab conditions where only the panel is visible and the exact multiple material is played on calibrated sets of the same price bracket/brand name/technology generation), it is a little based on what a persons preconceived notions for IQ are and what they have heard of certain technologies.

Erm, but dont let that put you off.

 

[Mintmaster]

Contrast is a misnomer .. Contrast is black level and CRT's still beat Plasma's for black levels.

The problem with CRTs is that they usually have a pretty bad ANSI contrast. If part of the screen is bright, the rest cannot be very black. For this reason I always thought it was rather silly to refer to them as "king of blacks".

The Panny's are getting close. I heard their upcoming models being shown at CES with a 20,000:1 (i know, marketing term) contrast ratio are quite impressive. Only 1.5 more weeks!

That would be pretty cool if true. I personally think once you get above 5,000:1 measured, it's pretty damn good and further improvements are pretty negligible.

 

[Gubbi]

Pioneer's new 8th generation should also have 80% lower minimum light output. The technology behind this is apparently the same as in the Panasonics (co-signed/developed patent).

Cheers

 

[thegrommit]

Another thing to take into account is the cabling:

Antenna
Pros:
- Always works
Cons:
- Bad signal quality

I believe those only apply to analog signals. You can either receive an ATSC signal, or you can't - resulting in spectacular image quality or nothing at all.

 

[pcchen]

I believe those only apply to analog signals. You can either receive an ATSC signal, or you can't - resulting in spectacular image quality or nothing at all.

You can get a partial digital signal. Small error in a MPEG-2 stream may cause blocky effects in video (or popping in audio, but less likely than video because audio data is much smaller than video data). In a bad condition you may get a constantly "blocky" MPEG-2 stream.