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Automatic Brightness Limiter Technology (Applies to CRT, Plasma, and for Now OLED)

post #1 of 21
Thread Starter 
Let's imagine a picture with a small, bright white box. If your display uses Automatic Brightness Limiter technology, by enlargening that white box, the display dims. From what I understand, this is a way to protect the components in the panels. However, it decreases the dynamic range of the picture. I was excited about OLED technology until I read reports that the LG 55EA9800 and the Samsung KN55SC9 use ABL technology. Unless plasma and OLED eliminate this, I will stick with LCD displays with bright backlighting and high static contrast ratios. The Samsung UN##ES8000, Samsung UN##F5000,, Samsung UN##F7100, Sony KDL-##W900A, Sony XBR-##HX850, Sony XBR-##HX950, and Sony XBR-##X900A come to mind. These displays have reported contrast ratios of at least 4000:1 and maximum luminance levels of at least 345 CD/M2, good color accuracy, and no ABL! In case you wonder how I'm researching this stuff and getting my info, after Binging, I discovered that www.televisioninfo.com has at least one ISF-certified staff member calibrating and measuring minimum luminance level, maximum luminance level, contrast ratio, color characteristics, and viewing angle. Considering that I don't drive, browsing that site is as helpful as trying these TVs out locally!
Edited by Big C - 8/19/13 at 5:23am
post #2 of 21
Otherwise known as the automatic brightness limiter control circuitry. Not even on the radar of concern for me, though there is a vocal minority who are incessantly perturbed by it. The most noticeable real-world content in which it rears its head is during commercial breaks with bright solid colors on full-screen.
post #3 of 21
Thread Starter 
Quote:
Originally Posted by vinnie97 View Post

Otherwise known as the automatic brightness limiter control circuitry. Not even on the radar of concern for me, though there is a vocal minority who are incessantly perturbed by it. The most noticeable real-world content in which it rears its head is during commercial breaks with bright solid colors on full-screen.
When privately exchanging e-mails with one of the people at televisioninfo, I was told to call it 'white falloff.' To me, it's like applying ALC and DRC to audio. While keeping dialog and action at an equal volume, it does avoid disturbing others, as well as possibly risking gradual hearing loss. However, it also decreases that real-life impact of the sound. I think the same applies with auto-brightness or white falloff. I believe that if you can avoid it, by all means, do so! And the reason I listed the TVs I listed is because of their contrast ratios, maximum luminance, and color performance, while eliminating auto-brightness or white falloff. So at this point in my AV journey, backlit LCD panels are my preferable display type.
post #4 of 21
You will see it most frequently referenced around here as ABL for short. Anyway, I can't agree...nonapparent ABL is preferable over LCDs. In fact, if I were to bother with LCD, it would have to be a full-array LED, the likes of which are no longer in production (maybe one of those Sony models, though I believe it's out of production). The nearly 30,000:1 contrast ratio of the ZT60 easily outweighs any overblown concerns about ABL.
post #5 of 21
Quote:
Originally Posted by Big C View Post

When privately exchanging e-mails with one of the people at televisioninfo, I was told to call it 'white falloff.'

Evidence that "televisioninfo" is not a place to go for television info.
Quote:
To me, it's like applying ALC and DRC to audio. While keeping dialog and action at an equal volume, it does avoid disturbing others, as well as possibly risking gradual hearing loss. However, it also decreases that real-life impact of the sound. I think the same applies with auto-brightness or white falloff.

I believe that if you can avoid it, by all means, do so![/quote]

Ugh. No.

On the one hand, the part where you are protecting your ears from hearing loss with headphones justifies limiting volumes forever with headphones via things like DRC. Hearing loss is forever. You won't go blind from over bright peak whites.

That said, when you are watching in darkness or near darkness, over bright whites do something very insidious that can absolutely destroy the video quality of what you're watching for the next 10-30 minutes. if you get "hit" with a too-white/too-bright scenes, your pupils will constrict -- rapidly -- to protect your eyes. Good stuff. Unfortunately, the dilation you'll need to enjoy the subsequent dark scenes that might exist will take many, many minutes. No way around the biology of this. Doubt me? Try going from a bright bathroom into your dark bedroom. See how well you can "see in the dark". Sit around for 10-15 minutes. Then try again. Amazing difference. ABL is usually deployed because of technological limitation, but a properly calibrated LCD will have its peak white limited in cinema/movie mode so you don't blow out your eyes.
Quote:
And the reason I listed the TVs I listed is because of their contrast ratios, maximum luminance, and color performance, while eliminating auto-brightness or white falloff. So at this point in my AV journey, backlit LCD panels are my preferable display type.

Essentially no one makes backlit LCD panels, locally dimmed or otherwise. You like something that more or less doesn't exist.
Quote:
Originally Posted by vinnie97 View Post

You will see it most frequently referenced around here as ABL for short. Anyway, I can't agree...nonapparent ABL is preferable over LCDs. In fact, if I were to bother with LCD, it would have to be a full-array LED, the likes of which are no longer in production (maybe one of those Sony models, though I believe it's out of production). The nearly 30,000:1 contrast ratio of the ZT60 easily outweighs any overblown concerns about ABL.

Yep.
post #6 of 21
Quote:
Originally Posted by vinnie97 View Post

Otherwise known as the automatic brightness limiter control circuitry. Not even on the radar of concern for me, though there is a vocal minority who are incessantly perturbed by it. The most noticeable real-world content in which it rears its head is during commercial breaks with bright solid colors on full-screen.
Actually, I would argue that it's quite noticeable in bright outdoor scenes in films, and it is most noticeable if you play games or use a computer hooked up to the display - those typically have much higher average picture levels than film.
Quote:
Originally Posted by vinnie97 View Post

You will see it most frequently referenced around here as ABL for short. Anyway, I can't agree...nonapparent ABL is preferable over LCDs.
Unless they can get plasmas back to the level that CRTs were at, where you only lost ~10% brightness when going from a 1% area pattern to a 100% area pattern, I would not call it "nonapparent". Most plasmas are still losing a significant amount of brightness. The Kuros lost 50% for example.

What is also important, is when that brightness loss occurs. The Kuro TVs started to lose brightness around 20-25%, whereas the Kuro Monitors started to lose brightness after about 50% area. So the overall ABL amount may have been the same (about 50% brightness loss) but the impact of the ABL was significantly reduced on the monitors.

It's really a shame that there are no review sites out there which do proper ABL testing of plasma displays, and that it will likely continue with OLEDs. I think it's an important metric to use when comparing displays.
A number of LCDs now have an optional software-based "ABL" and it would have been nice to see how closely that emulates the behavior of other displays.

Another factor is that with Plasma displays, this seems to be a fixed adjustment. No matter what level contrast was at on the Kuros, you always saw brightness start to drop at 25/50% area, and you always saw that ~50% brightness loss going from 1% area to 100%.
With a CRT, as you reduced the contrast control, the ABL was relaxed so the brightness loss was reduced.
This seems like it may be the case with OLED, as one review has shown that Sony's OLED monitors have no ABL when set to ~70% contrast.
Quote:
Originally Posted by rogo View Post

That said, when you are watching in darkness or near darkness, over bright whites do something very insidious that can absolutely destroy the video quality of what you're watching for the next 10-30 minutes. if you get "hit" with a too-white/too-bright scenes, your pupils will constrict -- rapidly -- to protect your eyes. Good stuff. Unfortunately, the dilation you'll need to enjoy the subsequent dark scenes that might exist will take many, many minutes. No way around the biology of this. Doubt me? Try going from a bright bathroom into your dark bedroom. See how well you can "see in the dark". Sit around for 10-15 minutes. Then try again. Amazing difference. ABL is usually deployed because of technological limitation, but a properly calibrated LCD will have its peak white limited in cinema/movie mode so you don't blow out your eyes.
What's interesting about this, is that there are some people that argue for the use of ABL based on this type of example. If you display a bright beach scene on the TV in a dark room, it will dim the picture and "protect" your eyes from the brightness.
The problem is that you effectively have two "irises" in action when an ABL is in effect - your eye and the ABL. If you display a bright beach scene on the TV, the plasma dims it - but the expectation of human perception is that your iris should be closing and restricting the brightness when something is bright. That your iris can stay wide open without having to adjust to a "bright" scene gives the perception that the plasma TV is dull.

The inverse is also a problem. I follow the calibration standards to the letter, and so my television is calibrated to a peak white of 100 cd/m2. This means that white is at 100cd/m2 whether it's the full screen, or a small area.
With a plasma display, if you calibrate it to a peak white of 100cd/m2 (peak white being a 1% area) you may have an average brightness of ~75cd/m2 and it will drop all the way down to 50cd/m2 with a full white screen. This means that regular viewing is very dull.
Some people opt to calibrate the display using a 15-25% pattern rather than following the spec and using a 1% area pattern. This means that your brightness range might now be 150-75cd/m2, so now when you are viewing dark scenes, any bright lights (e.g. flashlights) are piercingly bright.
It's even worse if you were to decide that you wanted the display to never drop below 100cd/m2 (a calibrated LCD should not) because then your brightness range is 200-100cd/m2 and the average picture level is going to be above 100cd/m2 most of the time.
post #7 of 21
first time I have seen the term White Falloff for what we commonly call ABL: I think the thread title should be edited to add ABL

I first saw ABL on a plasma watching Court TV: it was a relatively static courtroom scene and after a few seconds you could always see the screen dim: at first I thought it was a defect in the display...

Question: I always thought ABL was just a function added to limit power supply output: so it would not be over driven for long periods of time: reading this thread describes other reasons too?

if I noticed aggressive ABL on a $9-15k OLED I would be concerned...
post #8 of 21
I would never dream of using a plasma for a computer monitor. Some may be more susceptible to the phenomenon, but an intelligent algorithm will make it unnoticeable for the majority of viewing, especially as it relates to films. Hockey (and related snow-based sports like snowboarding and skiing), bright advertisements, and computing will be the types of content that have the greatest susceptibility to this "feature." That said, the ZT60 I have showed no visibly detectable dimming when watching the recent snowboarding film, Flight, and for typical viewing, I simply didn't notice it on the Kuro during the four+ years I had it (movies being the predominant content).
post #9 of 21
Thread Starter 
Chronoptimist, yes. I believe at least the Sony KDL-##W802A has ABL. To my surprise, considering that its peak brightness is only 198 CD/M2, it really doesn't need it! And if the other Sonys I mentioned have it, I would choose to turn it off.

Rogo, as far as protecting hearing is concerned, I play the loudest portion. As long as it's not so loud I get post-ringing in my ears, I'm fine with that. If the dialog should get a little too weak, I'd just squint my ear. Although I have played 24-bit DTS-HD Master Audio and LPCM streams from my Blu-ray discs without any DRC and ALC and have had no problems with post-ringing and squinting. Sorry to go offtopic, but I feel that in order to understand ABL for video, comparing it to DRC and ALC for audio would help you guys to understand it from my point of view. All the dedicated audiophiles here at AVS prefer not to use DRC, ALC, etc.. That's why I'm surprised that AVS's dedicated videophiles aren't bothered by ABL!

Also, rogo, you said that backlit LCD doesn't exist. There are four types of LCD backlighting--CCFL, full-array LED, direct LED (which is similar to full-array, but uses less LEDs), and edge-LED.

After hanging around AVS since April of 2008, I am used to the term ABL. Yet www.televisioninfo.com is the only place I can find which actually gives CD/M2 values for more recent displays. There is at least one ISF-certified staff member at televisioninfo. They even explain how they test, and it all sounds pretty legit to me. Also, manufacturers allow televisioninfo hands-on experience with displays which haven't even hit the shelves yet. If you guys know of a better online database than www.televisioninfo.com which gives the scientific details I'm interested in (black level and maximum luminance in CD/M2, description of color performance, and viewing angle), please post a link.
Edited by Big C - 8/17/13 at 6:58am
post #10 of 21

Perhaps this is horribly dated info, and far below the level of conversation here for you ISF folks, but I recall the issue historically being far more than just white, and not just a problem with hurting anything in hardware.  At least in the early displays one of the fundamental problems of the RGB color model is how poorly it natively maps to RGB light sources (of any kind) even if you confine your problem to light output.

 

In an RGB color model, the overall luminance of a display isn't taken into account.  For instance: you get green by turning on green (Using 30-59-11, green is roughly 59% of the overall luminance impact in your eyes).  You get red by turning on red (red is roughly 30% of the overall luminance impact).  However, when you add the two to get yellow, you end up with *two light sources* on at the same time, much more overall light coming out, not just the triggering of the red and green cones in your eyes.  This ended up with a skewed blasting of any combination of light sources, not just white, which did *always* end up as a flashlight.
 

post #11 of 21
Quote:
Originally Posted by markrubin View Post

first time I have seen the term White Falloff for what we commonly call ABL
Me too. I thought this was going to be about uniformity problems.
Quote:
Originally Posted by Big C View Post

Chronoptimist, yes. I believe at least the Sony KDL-##W802A has ABL.
Sony has had it for some time now - it's the "Auto Light Limiter" control, and it lets you choose from Off/Low/Medium/High.
post #12 of 21
Quote:
Originally Posted by Chronoptimist View Post

Sony has had it for some time now - it's the "Auto Light Limiter" control, and it lets you choose from Off/Low/Medium/High.

Didn't that review of the 25" Sony OLED monitor also mention various CRT emulation features that were intentionally added to the display to preserve the response of the previous CRT monitors they replaced? I don't recall if it was ABL, gamma, or some other attribute. It's kind of funny that after all these years we're still building displays to emulate a technology that's long since disappeared from the market. I'm not sure if we'll ever escape interlacing, /1.001 fps scaling, CRT gamma curves, CRT color spaces, etc.
post #13 of 21
Thread Starter 
Quote:
Originally Posted by Wizziwig View Post

Quote:
Originally Posted by Chronoptimist View Post

Sony has had it for some time now - it's the "Auto Light Limiter" control, and it lets you choose from Off/Low/Medium/High.

Didn't that review of the 25" Sony OLED monitor also mention various CRT emulation features that were intentionally added to the display to preserve the response of the previous CRT monitors they replaced? I don't recall if it was ABL, gamma, or some other attribute. It's kind of funny that after all these years we're still building displays to emulate a technology that's long since disappeared from the market. I'm not sure if we'll ever escape interlacing, /1.001 fps scaling, CRT gamma curves, CRT color spaces, etc.
I thought the idea behind these other technologies was to IMPROVE upon CRT, not just to produce something thinner that does the same thing. I say that if you can disable Auto Light Limiters, Automatic Brightness Limiters, etc., turn them off, especially if you're not going to break anything! I hope the Samsungs I mentioned in post # 1 don't have such a feature, or if they do, the feature can be turned off.
post #14 of 21
Quote:
Originally Posted by Wizziwig View Post

Didn't that review of the 25" Sony OLED monitor also mention various CRT emulation features that were intentionally added to the display to preserve the response of the previous CRT monitors they replaced? I don't recall if it was ABL, gamma, or some other attribute. It's kind of funny that after all these years we're still building displays to emulate a technology that's long since disappeared from the market. I'm not sure if we'll ever escape interlacing, /1.001 fps scaling, CRT gamma curves, CRT color spaces, etc.
The CRT mode was to emulate a BVM's color and gamma attributes, so it could be a direct replacement for them. I don't think the ABL was a factor in that - or at least I haven't seen anyone mention it.
ABL just seems to be an issue you have to deal with when using emissive displays.
Quote:
Originally Posted by Big C View Post

I thought the idea behind these other technologies was to IMPROVE upon CRT, not just to produce something thinner that does the same thing. I say that if you can disable Auto Light Limiters, Automatic Brightness Limiters, etc., turn them off, especially if you're not going to break anything! I hope the Samsungs I mentioned in post # 1 don't have such a feature, or if they do, the feature can be turned off.
I was just pointing out that Sony's LCDs offer an ABL implementation for people that want it. It's disabled by default in all picture modes.
post #15 of 21
Thread Starter 
Quote:
Originally Posted by Chronoptimist View Post

Quote:
Originally Posted by Wizziwig View Post

Didn't that review of the 25" Sony OLED monitor also mention various CRT emulation features that were intentionally added to the display to preserve the response of the previous CRT monitors they replaced? I don't recall if it was ABL, gamma, or some other attribute. It's kind of funny that after all these years we're still building displays to emulate a technology that's long since disappeared from the market. I'm not sure if we'll ever escape interlacing, /1.001 fps scaling, CRT gamma curves, CRT color spaces, etc.
The CRT mode was to emulate a BVM's color and gamma attributes, so it could be a direct replacement for them. I don't think the ABL was a factor in that - or at least I haven't seen anyone mention it.
ABL just seems to be an issue you have to deal with when using emissive displays.
Quote:
Originally Posted by Big C View Post

I thought the idea behind these other technologies was to IMPROVE upon CRT, not just to produce something thinner that does the same thing. I say that if you can disable Auto Light Limiters, Automatic Brightness Limiters, etc., turn them off, especially if you're not going to break anything! I hope the Samsungs I mentioned in post # 1 don't have such a feature, or if they do, the feature can be turned off.
I was just pointing out that Sony's LCDs offer an ABL implementation for people that want it. It's disabled by default in all picture modes.
Unless they do away with ABL, I won't be getting a CRT, plasma, OLED, or anything emissive--used or new. If color is an issue with nonemissive LCD panels, I understand Sony's Triluminos panels have better color than standard LCD panels. In fact, I'd love to get the Sony KDL-##W900A, except they don't make one in my size. Right now, the Samsung UN40F5000 is reported to have the best contrast ratio, maximum luminance, and good color for an LCD panel, and no ABL! So for now, the TVs in my first post are the ones I would recommend for those serious about good picture in all lighting conditions.
post #16 of 21
Count me in the camp that could care less about ABL. I have a Kuro 141 that is properly calibrated. I use it in a dark room. The only time I ever even notice the ABL is during an all white screen, normally only in a commercial. Other than live sports, I never seen commercials as I use the DVR. As for hockey, I see no evidence of it during the games. The ice looks just like it does when I am at the games. For me, ABL is a non issue.
post #17 of 21
Thread Starter 
Quote:
Originally Posted by JWhip View Post

Count me in the camp that could care less about ABL. I have a Kuro 141 that is properly calibrated. I use it in a dark room. The only time I ever even notice the ABL is during an all white screen, normally only in a commercial. Other than live sports, I never seen commercials as I use the DVR. As for hockey, I see no evidence of it during the games. The ice looks just like it does when I am at the games. For me, ABL is a non issue.
I guess if you have one of the emissive panels (CRT, plasma, or OLED), you could always turn down the overall panel brightness and/or the contrast. However, if watching TV during the day, you'd better keep the curtains shut and the lights out, or else, make TV time a nighttime activity because you will probably wind up with a maximum luminance of 80 CD/M2 or less! When displaying an all-black picture, how bad is a minimum luminance of 0.07 CD/M2? Is that going to be unbearable at night? The Samsung UN##F5000 has a maximum luminance of 347.30 CD/M2, giving it a contrast ratio of almost 5000:1, possibly making this TV good for daytime and nighttime use.
post #18 of 21
My theater room has room blackening shades as well as curtains so I can control the lighting. It is where I do any critical viewing. Casual viewing is done the family room with an older commercial Panny, which still looks pretty good, even during the day.
post #19 of 21
Even in moderate light on the majority of content, ABL is not a showstopping problem on today's plasmas.
post #20 of 21
Thread Starter 
I guess if you love emissive panel types and CRT is your favorite, OLED seems to be its true replacement. I just don't like the ABL. I can see I made my point, and for me, until they get rid of ABL, LCD panels are the way to go!
post #21 of 21
Enoy! I just like the screen type that offers the all-around best PQ for cinematic viewing in a darkened environment. That's still plasma in 2013 (unless you want a curved screen).
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