Are LEDs a joke??

[FirstReflection]

3db,

my experience has been that all currently available LCDs that use local dimming LEDs as the backlight do, indeed, show "blooming" around bright objects on a dark background. There is a simple explanation for why this is so:

The LEDs are divided into several "blocks" - each block is capable of dimming independently of all the other "blocks". But the "blocks" are relatively large compared to the individual LCD pixels. So far, all local dimming LED backlit LCD displays have used fewer than 100 "blocks". So each "block" is responsible for illuminating some 20,000 or more pixels!

It's easy to imagine how a "block" of the LED backlight that is illuminating more than 20,000 pixels would be unable to provide pixel-for-pixel precision. Let's just imagine a 140 pixel x 140 pixel "block". And within that one "block", let's imagine that there is a 70 pixel x 70 pixel white square surrounded by black. In order to create the 70 pixel x 70 pixel white square, then entire "block" of the LED backlight goes to its peak brightness, effectively creating a 140 pixel x 140 pixel sized backlight. The 70 x 70 pixel white square gets the light that it needs, but the entire surrounding black area also has the LED backlight "block" shining behind it. The pixels that are supposed to be black still allow a little bit of that light to shine through and this creates the "halo" around the 70 x 70 pixel white square. It's supposed to be a small white square on an all-black background, but because the LED backlight "block" is too large, you end up with "blooming" around the bright, white square.

This is the case with all current local-dimming LED backlit LCD displays. But it doesn't mean it will always be this way. Toshiba announced their "Cell Regza" local-dimming display that uses 512 independent "blocks" of LED backlights, so we are already seeing an increase in the number of independent "blocks", which will eventually lead to enough precision that "blooming" will be eliminated.

"Blooming" is not visible with edge-lit LED backlit LCD displays because the backlight is constantly on - just like a traditional CCFL backlit LCD display. But with the light coming from the edges, illumination of the screen is uneven. Almost all edge-lit displays also alter the output of the LED edge-lights in order to try and increase perceived contrast. This leads to a "pumping" of the baseline illumination level, which can sometimes be noticeable.

Bottom line is that LED backlit LCDs are promising, but right this second, there isn't a single model that produces picture quality that is equal to the best plasmas or even the best CCFL backlit LCDs for that matter. Doesn't mean the technology is bad or that the current models themselves even look all that bad. It's just that there are better displays available right now for less money, so why not pay less and get more?

 

[jostenmeat]

double post accidentally upon edit.

 

[jostenmeat]

Are you sure about those distances? I was 6' away from my 47" screen and I found that still to be too close. I found my eyes scanning the screen back and forth from that distance. My 47" is now 10" feet away and its perfect. No more scanning the screen to get the whole picture.

We ALL are sure, including yourself. In the end, personal preference is the only thing that matters.

The 30-32 degrees that FR has been speaking of has to do with being able to resolve 1080p, to the full extent of what it can offer while assuming 20/20 vision, but not any closer where the PQ may become "softer".

This is a tweaking of the well known Carton Bale graph, as done by ThA TriXtA. As you can see, for your 47' from 10 ft, you can't even fully resolve 720p, and forget 1080. Then again, you probably don't have a bluray player do you . . .

I have more to add. It's commonly said that 36 degree THX rec, well above the figure given by FirstReflection, is the starting point.

You can use this helpful plug n play calculator:
http://myhometheater.homestead.com/viewingdistancecalculator.html

However, there are experts who say 36 deg is for the very back row of a theater.

My front row is 42, and the rear row is slightly over 30. I have directly compared the immersion to two movies I've seen this year in "digital" DLP theaters. (This is probably the third or fourth time I've talked about this experience at AH). Terminator, from 3/4 back, was just about identical with my 42 deg viewing angle. UP, from about 1/4-1/3 from screen, was significantly more immerssive. So, I've been led to believe that even the long standing THX rec might becoming obsolete??

Yet another thing to consider is the great variances of aspect ratio. The THX rec assumes a "full screen" 16:9, but there are many "smaller" ARs. Many of the movies that are in the 2.35-2.40 AR range means that you are losing about one-third of your display size. So, I do think usage plays a key role. If you watch mostly TV, that's nearly all in 1.77:1, AND the signals are usually unforgiving in the sense that they're overcompressed, and I would also opt for a smaller viewing angle.

For me, however, I don't watch TV, and exclusively watch blurays. Therefore, I say bring it on!

btw, I played for an entire week with different sizes by firing the PJ at the wall. As always, YMMV!

 

[clouso]

So just because you have had the blooming factor happen on your LCD means everyone is going to have it??? I hate to burst your bubble but you are more in the minority than you know.

you are not busting my bubble cause if you read all the reviews about led lcd's there is mention about blooming in all of them...the sony's..samsung's and toshiba's all have that issue

 

[jostenmeat]

I love front projection too. I often recommend front projection setups where the viewing environment will facilitate them because they allow for substantially larger screen sizes at very reasonable prices. But it is only in rare cases (in my experience) that a front projection system works well in a living room. Most people just don't want to make their living room pitch black - or as close to pitch black as possible. For dedicated theatres, it's often a much better choice! But for a living room setup, the amount of light during the day is usually too bright to allow a front projection system to look good.

Or have cake and eat it with tab tensioned ceiling recessed screen, or a Dalite HP manual for a lot less money, while further rejecting ambient light, and increasing on-axis gain. $600 plasma behind screen.

Budget at $2,200? Could be a problem. $250 screen, $600 plasma, Optoma $1000. Actually . . . .

 

[lsiberian]

I love front projection too. I often recommend front projection setups where the viewing environment will facilitate them because they allow for substantially larger screen sizes at very reasonable prices. But it is only in rare cases (in my experience) that a front projection system works well in a living room. Most people just don't want to make their living room pitch black - or as close to pitch black as possible. For dedicated theatres, it's often a much better choice! But for a living room setup, the amount of light during the day is usually too bright to allow a front projection system to look good.

The room doesn't actually have to be pitch black to run a PJ well. I actually run one in my living room during the day and even with some lights on. You will need curtains for the windows and or doors, but you can get tension rod ones pretty cheap that look really nice. I know it's a crazy concept to some, but it's certainly doable in many cases. Again it's an option to look at. Not the be-all end-all.

 

[timoteo]

Again...thank you FR because i came back to ask another question which was regarding local dimming and BAM! you had read my mind and cleared that up for me. Thanks.

Bad news on my end however. The house that my wife & i were hoping to get was rented to someone else who offered more $ per month. Oh well! Good news though is that i am working on my lady about getting a TV even sooner to help with my "grieving process." Hope it works!

A buddy of mine just bought a 58" Samsung 860 Plasma. He was telling me that he had paused a DVD for a few minutes and when he went back to watching the movie, he could still see the pause word lightly burned in the screen for a good 5-10min. The same thing happened with some other words from his sat menu.

Is that common with most plasmas?

Is that because its brand new & will go away after a break in period?

He is going to have his screen profesionally calibrated. But they told him to wait until he has put at least 120hrs on it.

After recieving good feedback from this site about my upcoming tv buy, i have started to lean on the side of a plasma instead of an LCD or LED/LCD. However i would not be able to handle that problem that he is having if that is the norm.

Samsung is releasing a new 8500LED series that will be backlit as opposed to sidelit...Any comments?...Worth the wait (2months)?

Im gonna make a call to that dealer i mentioned b4 to see if he could get his hands on the KRP500m that you guys recommended. Want to see how much he could get it to me for, if he can!

 

[3db]

We ALL are sure, including yourself. In the end, personal preference is the only thing that matters.

The 30-32 degrees that FR has been speaking of has to do with being able to resolve 1080p, to the full extent of what it can offer while assuming 20/20 vision, but not any closer where the PQ may become "softer".

This is a tweaking of the well known Carton Bale graph, as done by ThA TriXtA. As you can see, for your 47' from 10 ft, you can't even fully resolve 720p, and forget 1080. Then again, you probably don't have a bluray player do you . . .

I have more to add. It's commonly said that 36 degree THX rec, well above the figure given by FirstReflection, is the starting point.

You can use this helpful plug n play calculator:
http://myhometheater.homestead.com/viewingdistancecalculator.html

However, there are experts who say 36 deg is for the very back row of a theater.

My front row is 42, and the rear row is slightly over 30. I have directly compared the immersion to two movies I've seen this year in "digital" DLP theaters. (This is probably the third or fourth time I've talked about this experience at AH). Terminator, from 3/4 back, was just about identical with my 42 deg viewing angle. UP, from about 1/4-1/3 from screen, was significantly more immerssive. So, I've been led to believe that even the long standing THX rec might becoming obsolete??

Yet another thing to consider is the great variances of aspect ratio. The THX rec assumes a "full screen" 16:9, but there are many "smaller" ARs. Many of the movies that are in the 2.35-2.40 AR range means that you are losing about one-third of your display size. So, I do think usage plays a key role. If you watch mostly TV, that's nearly all in 1.77:1, AND the signals are usually unforgiving in the sense that they're overcompressed, and I would also opt for a smaller viewing angle.

For me, however, I don't watch TV, and exclusively watch blurays. Therefore, I say bring it on!

btw, I played for an entire week with different sizes by firing the PJ at the wall. As always, YMMV!

Maybe I wasn't clear... and putting all of these THX specs aside for a moment. I was sitting right in front of the TV 0 degree viewing angle.. and I was watching MArtin Scorcese's production on "The Blue" and the screen was displaying an interview between two people. My eyes kept shifting back and forth between the interviewer and the person interviewed. I could not see the whole picture at once.. analogous to looking at a 747 to close you only see a bit of the plane but when you stand further back you see the whole thing.. This is the distance I was questioning based on what I saw.

 

[3db]

3db,

my experience has been that all currently available LCDs that use local dimming LEDs as the backlight do, indeed, show "blooming" around bright objects on a dark background. There is a simple explanation for why this is so:

The LEDs are divided into several "blocks" - each block is capable of dimming independently of all the other "blocks". But the "blocks" are relatively large compared to the individual LCD pixels. So far, all local dimming LED backlit LCD displays have used fewer than 100 "blocks". So each "block" is responsible for illuminating some 20,000 or more pixels!

It's easy to imagine how a "block" of the LED backlight that is illuminating more than 20,000 pixels would be unable to provide pixel-for-pixel precision. Let's just imagine a 140 pixel x 140 pixel "block". And within that one "block", let's imagine that there is a 70 pixel x 70 pixel white square surrounded by black. In order to create the 70 pixel x 70 pixel white square, then entire "block" of the LED backlight goes to its peak brightness, effectively creating a 140 pixel x 140 pixel sized backlight. The 70 x 70 pixel white square gets the light that it needs, but the entire surrounding black area also has the LED backlight "block" shining behind it. The pixels that are supposed to be black still allow a little bit of that light to shine through and this creates the "halo" around the 70 x 70 pixel white square. It's supposed to be a small white square on an all-black background, but because the LED backlight "block" is too large, you end up with "blooming" around the bright, white square.

This is the case with all current local-dimming LED backlit LCD displays. But it doesn't mean it will always be this way. Toshiba announced their "Cell Regza" local-dimming display that uses 512 independent "blocks" of LED backlights, so we are already seeing an increase in the number of independent "blocks", which will eventually lead to enough precision that "blooming" will be eliminated.

"Blooming" is not visible with edge-lit LED backlit LCD displays because the backlight is constantly on - just like a traditional CCFL backlit LCD display. But with the light coming from the edges, illumination of the screen is uneven. Almost all edge-lit displays also alter the output of the LED edge-lights in order to try and increase perceived contrast. This leads to a "pumping" of the baseline illumination level, which can sometimes be noticeable.

Bottom line is that LED backlit LCDs are promising, but right this second, there isn't a single model that produces picture quality that is equal to the best plasmas or even the best CCFL backlit LCDs for that matter. Doesn't mean the technology is bad or that the current models themselves even look all that bad. It's just that there are better displays available right now for less money, so why not pay less and get more?

thx for the info....I'll have to check this out on my LCD to see if I can notice it. I watcched Underworld Three last night ....mostly dark movie but there is a scene where the light gets bright on one part of the acreen.. is that a good place to check?....

about plasma vs lcd... i've always manitained that plasma is better than lcd but here in Canada, Plasma still runs $300 to $500 more for the equivalent screen size and 1080p

 

[audiohonic65]

Thanks a lot for this fair advice, I was also contemplating the idea of buying a plasma TV. Now, I am sure about my decision.

 

[audiohonic65]

This graph is pretty impressive, you have done some really good survey on this.

 

[audiohonic65]

Plasma is on top, LCD is good in terms of color reproduction, but not to the level of Plasmas. But I think the Samsung LED LCD can give a good fight while comparing.

 

[jostenmeat]

Maybe I wasn't clear... and putting all of these THX specs aside for a moment. I was sitting right in front of the TV 0 degree viewing angle.. and I was watching MArtin Scorcese's production on "The Blue" and the screen was displaying an interview between two people. My eyes kept shifting back and forth between the interviewer and the person interviewed. I could not see the whole picture at once.. analogous to looking at a 747 to close you only see a bit of the plane but when you stand further back you see the whole thing.. This is the distance I was questioning based on what I saw.

I understand. You know what's so funny 3db, is that when I got into this hobby, I kept comparing stuff to real life. Oh, man, I hated excessive sibilance from a bad speaker, and never looking for it before, I started paying attention to people who spoke with more natural sibilance than others, lol. Or... the whole motion blur thing, I started paying more attention to when I see it (for example, just wave your hand in front of your face: motion blur!).

What I'm getting at is if you are with, say, two friends at a table, and you're watching them in animated discussion, you will be moving/shifting your eyes. Unless you are at the extreme side of one row, perhaps, but if you are in a triangular formation, you will be shifting your eyes, period. For me, I think it's cool that I'm shifting my eyes, and everywhere I look, it's gorgeous.

 

[3db]

I understand. You know what's so funny 3db, is that when I got into this hobby, I kept comparing stuff to real life. Oh, man, I hated excessive sibilance from a bad speaker, and never looking for it before, I started paying attention to people who spoke with more natural sibilance than others, lol. Or... the whole motion blur thing, I started paying more attention to when I see it (for example, just wave your hand in front of your face: motion blur!).

What I'm getting at is if you are with, say, two friends at a table, and you're watching them in animated discussion, you will be moving/shifting your eyes. Unless you are at the extreme side of one row, perhaps, but if you are in a triangular formation, you will be shifting your eyes, period. For me, I think it's cool that I'm shifting my eyes, and everywhere I look, it's gorgeous.

Yeah know, you just might have a point there . I guess I'm just getting into the big screen thing coming from a 32" TV less than 3 monthes ago and I'm still used to seeing everything at once.

 

[FirstReflection]

The choice of screen size for your given distance is definitely a matter of personal preference. Some people go to a movie theatre and sit in the front row. Other people will always sit at the very back.

I never meant to say that you HAVE to get a screen size that provides a 30 degree field of view. A 30 or 32 degree field of view is simply the size that SMPTE recommends. And it is based upon human perception.

The human eye needs a gap of 1 arc minute (1/60th of a degree) between two points in order to discern those two points as being separate. If the two points are closer together than 1 arc minute, the human eye will perceive them as a single point.

So we never want to sit so close that the gap between pixels becomes equal to or greater than 1 arc minute because that will enable us to see every pixel as individual and separate! At the same time, if we are trying to see as much detail as possible, we basically want each pixel to completely fill 1 arc minute of our field of view.

For example, let's imagine a white line - one pixel wide - that runs from the top of the screen to the bottom of the screen. Now let's imagine a black line - again, one pixel wide - that is directly to the right of that first, white line. And then, let's imagine a second white line - one pixel wide) that is directly to the right of the black line.

If we are to see the full detail, we should be able to make out two white lines with a black line in between them. In order to do that, the black line must be at least 1 arc minute wide. If the black line is less than 1 arc minute wide, we will not perceive two white lines with a black line in between. Instead, we would perceive a single grey line!

So if the black line is 1 arc minute wide and the black line is one pixel wide, that means that one pixel would have to be 1 arc minute wide.

If there are 1920 pixels across the screen, and each pixel is 1 arc minute wide, then all 1920 pixels occupy exactly 32 degrees of our field of view

So my "ideal" screen size comes from calculating exactly how wide each pixel must be in our field of view in order for the human eye to be able to perceive every detail of the image. Sit any further back, and details begin to blur together. That white line-black line-white line pattern turns into a single grey line and detail is lost! But sit too close, and you begin to notice each individual pixel.

 

[FirstReflection]

timoteo,

what you described with your friend's Samsung plasma is "image retention". Many people mistake it for "burn-in". But burn-in is permanent. Image retention goes away eventually. And, as you said, your friend's Samsung plasma does return to normal after a few minutes.

When a plasma is brand new, it is at its absolute brightest. Over time, it gradually gets dimmer and dimmer. But during the first 200 hours or so, it dims proportionally more than any other time.

So that is why a professional calibrator will tell you to use the display for 200 hours or so before doing the full calibration. If you calibrate it when it is brand-spanking new, it will actually dim a fair bit and the calibration will be incorrect.

During those first 200 hours or so is when image retention is most noticeable. Due to the display being at its absolute brightest, image retention happens more easily. But it is not permanent and it does not actually "damage" the display in any way.

Most people do not calibrate their displays at all. They just take them out of the box, turn them on, and leave them in their default settings. Sadly, the default setting is often the "Vivid" mode, which we jokingly call "torch mode" because the light output is cranked to its maximum! Having the display be as bright as it possibly can definitely increases the chances of seeing image retention. Simply switching the display to its "cinema" or "movie" picture mode is often enough to eliminate or, at least, greatly reduce the visibility of image retention.

Bottom line: image retention is not a reason to avoid plasma displays. It is not permanent and it is not damaging the display.

When you first get a plasma, just put it in "cinema" or "movie" picture mode so that it is not in "vivid" picture mode and cranking out WAY more brightness than you need. Run it for 200 hours or so, and then go ahead and perform a full calibration

 

[FirstReflection]

timoteo,

regarding the new Samsung B8500 series. The UN B8500 series are local dimming LED backlit LCD displays. CNET reviewed the new B8500 series and was, overall, very positive - calling it the best LCD they've ever tested!

But there are still a number of negatives and they are the sort of negatives that can really make the B8500 series a bad choice for certain rooms.

Like all LED backlit LCDs so far, the B8500 series has (reportedly) bad off-axis viewing. It also has Samsung's super glossy screen surface, which I personally think is SUCH a shame because it basically makes their displays unwatchable in a well-lit room. Some people don't seem to mind the reflections, but I personally find them FAR too distracting to enjoy whatever I am watching.

The big plus is that the B8500 series reportedly shows less blooming than previous local dimming LED backlit LCD displays. But there is reportedly still SOME blooming.

All throughout the CNET review, the Pioneer Kuro plasmas are still mentioned as being better. And the Panasonic V10 and G10 plasmas are very close behind the Kuro plasmas, so you can extrapolate where the Panasonic plasmas would stand.

Myself, I like to be constantly reminded that ALL facets of a display need to be considered. It's all fine and well to go after the deepest black levels or the most accurate colour, but if those metrics come at the expense of something like a glossy screen or poor off-axis viewing, I personally believe that it is better to compromise on some metrics so that other metrics do not suffer too badly.

The Pioneer Kuro plasmas are basically a "no compromise" design. In EVERY facet, they are excellent. The Panasonic V10 plasmas give up a little bit in the way of black level retention and reflections in a well-lit room, but in all other ways, they are very nearly the equal of the Kuro plasmas.

From the reports on the UN B8500 series, the black levels are definitely excellent, as are the colour accuracy and simply the overall image when viewed in a dark room from straight on. But personally, that Samsung glossy screen is just a deal breaker because I find the reflections so incredibly distracting.

You might be different though and you might not find the reflections objectionable. One thing is certain though, and that is the price difference! The B8500 Samsungs are expensive and you can most definitely get a larger Panasonic plasma for less money and have much better off-axis viewing and a less reflective screen to boot!

 

[timoteo]

I am definately considering all aspects of a display befor making a final decision. That last post gave me more to think about thanks. The newest on my possible moving situation is that some family friends are offering my wife & i a good deal on a house to rent. The living room is 15.5'x19' however we will probably be setting about 12'-14' from the screen. So NOW that means an even bigger tv. Stoked that i can get a large tv but bummed im gonna have to up my $ limit a bit now! Move isnt for sure yet but is looking promising.

Ill be seeing my friend with the new plasma and will pass on the good info on his tv. Ill help him change the setting to "cinema." He paid about $2400-$2500 for that plasma...good price?

 

[AVRat]

Well, larger for less, Mitsubishi 73737: http://www.bestbuy.com/site/olspage.jsp?skuId=9301276&type=product&id=1218080216100

73837 review: http://hometheatermag.com/rearprojectiontvs/mitsubishi_wd-73837_dlp_rear-projection_hdtv/

I saw these on 9/19 in a local specialty shop with some calibration done. Picture was absolutely stunning!

 

[Amherst]

Timoteo, curious, have you found the display you want to purchase yet?