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TV backlight compensation (2020)

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Re: TV backlight compensation (2020)

#111

Post by Sohcahtoa82 »

autoexec wrote: post #52
BoorishBears wrote: post #36

Earlier quoted context omitted.

My XDR has been pretty flawless, and on the less exorbitantly priced end, I've had good experiences with a few business oriented IPS models (most recently the Samsung UR55). My main gripe is gaming monitors seem to be consistently the worst panels they can get their hands on. It seems like they realize gamers will put up with a lot of garbage in exchange for raw "power" and take full advantage of the fact. I'm 99% su…

If you fill your entire screen with nothing but a single solid color (try #FF6400) does it show up correctly? That is, without any gradient or areas of the screen where the color appears darker or lighter (especially around the edges or in the corners?). I've yet to find a modern monitor that doesn't have a problem with that basic test, which is pretty disappointing considering accurately representing a single color…

On my main monitor, a test like that fails spectacularly.

If I put a solid purple, then if my eyes are directly perpendicular to the very center of the screen, it works fine. As soon as I move up or down, either the top or bottom of the screen becomes very noticeably blue.

But in daily use, I never notice it. If I lean way back in my chair, then yeah, I'll need to adjust my screen to be able to see it.

But this is a 144 hz 1440p monitor I got for $400 brand new in 2015. Pixel response times are great. The monitor works exceptionally well on all the Blur busters tests. It is an amazing monitor for gaming...

...except in dark scenes. It's a TN panel, which by default kind of lacks in contrast and brightness, and so to make it look good, I had to tweak contrast, gamma, and brightness settings, and it results in some clipping. #020202 and #010101 look like they get rounded down to #000000, and #050505 and #040404 look like they're getting rounded down to #030303.

If I draw a pure black-to-white gradient, then there's noticeable banding. Like colors are only being represented in 7 bits per channel, and the darkest colors lose even more.

But again, in daily usage, especially in games (as long as it's not a dark scene) and videos, it's not even noticeable.

Re: TV backlight compensation (2020)

#112

Post by drumdude »

jagged-chisel wrote: post #55
drumdude wrote: post #21

I do this for a living. Sony digital cinema projectors use a type of LCD panel (SXRD) where the uniformity drifts over time. A special camera takes about 35 minutes to create a LUT to restore the projected image to a uniform white.

Is that 35 minutes spent collecting input, or calculating the LUT?

The camera handles everything automatically. It generates dynamic patterns on the screen and adjusts several times until it is satisfied with the result. It does this for red, green, blue, and white across 10IRE, 20IRE, ect up to 100IRE. The LUT is human readable and able to be uploaded and downloaded from the FPGA.

Re: TV backlight compensation (2020)

#113

Post by londons_explore »

CamperBob2 wrote: post #100
moffkalast wrote: post #97

Earlier quoted context omitted.

That is some top tier investigating and persistence, hats off. I would've used the excuse the upgrade the monitor lol.

Or replace the 30-cent capacitor that's likely causing it.

It's likely one of the power bond wires from the glass screen to the silicon IC. Without equipment stretching into the millions of dollars, you won't be fixing that.

Re: TV backlight compensation (2020)

#114

Post by ornornor »

empiricus wrote: post #59
serd wrote: post #22

Earlier quoted context omitted.

Could you share a photo? I'd really like to see that.

https://i.postimg.cc/1Xy6V5wb/oledburn.jpg not the greatest picture (some reflections). should have used a gray background, but I used red because this color is the most affected. The burnin is mostly harmless, but the middle blob is very annoying; yellow parts of the image become greenish when they get to the middle of the screen.

Ah that sucks. How old is the tv? And what’s the brightness in it?

My 3 year old Panasonic gets used a lot but we keep the brightness down to the 45–55% range (it’s plenty bright) to avoid burn in. We also don’t display static content on it. And when we do, it’s mostly from Kodi which dims itself after 10 min or so.

All that to say for those who are fearful of OLED because of burn in: don’t be. With some precautions, it’s fine. And having true blacks is absolutely glorious. I enjoy it every time I use the screen.

Re: TV backlight compensation (2020)

#115

Post by somat »

xattt wrote: post #60
franky47 wrote: post #44

Earlier quoted context omitted.

Funny how recent developments in AI have warped our comprehension of what is easy to ask to a computer vs what is hard. Obligatory related XKCD: https://xkcd.com/1425

AI is turning out to be the singularity that science fiction writers talked about. You just have no freaking idea what’s next at this point.

I am halfway convinced that the singularity has already occurred and has been ongoing from the 1700's* however, being carried along with it, you can't see it directly, you can only dimly sense it's tidal pull.

It is like a black hole. how long does it take to fall into a black hole? the answer is a surprising "just about forever" due to time itself dilating as you approach the center.

* think about it, mankind had been trundling about with effectively the same economy for many thousands of years then at some point about three hundred years ago it went exponential and has not slowed down.

Re: TV backlight compensation (2020)

#116

Post by GauntletWizard »

squeaky-clean wrote: post #101
lesuorac wrote: post #92

Earlier quoted context omitted.

Besides the fact that GPS already exists, it seems like it would take longer (~20 years) than the 5 years claimed to detect birds. > The GPS project was started by the U.S. Department of Defense in 1973. The first prototype spacecraft was launched in 1978 and the full constellation of 24 satellites became operational in 1993 https://en.wikipedia.org/wiki/Global_Positioning_System

Never forget to read the alt-text joke on an XCKD comic. The punchline on this one is based in some truth. > In the 60s, Marvin Minsky assigned a couple of undergrads to spend the summer programming a computer to use a camera to identify objects in a scene. He figured they'd have the problem solved by the end of the summer. Half a century later, we're still working on it. https://dspace.mit.edu/bitstream/handle/1721.…

What's really incredible to me is how right the prediction was, but also that it was real. In 2014, classifying images as "containing a bird" was a nigh-on-impossible task. Not an impossible one, and image classification was already in production use in limited forms with mapping agencies and the like, but beyond anyone's capability at the time. In 2017, Not Hotdog was a novelty app - Image classification was real, but limited, and didn't have a great reputation yet. By 2019, papers[1] were being written on image classification as a service and where their pitfalls were, but the idea was solid and sound; Today in 2022, it's something you'd have to research and test before buying for your startup but not a hard product to find.

[1]https://arxiv.org/abs/1906.07997

Re: TV backlight compensation (2020)

#117

Post by GauntletWizard »

MayeulC wrote: post #94
washadjeffmad wrote: post #67

Earlier quoted context omitted.

I imagine the process is Capture > Analyze > Generate > Apply > Repeat until all test images are within bounds and color matched, not stage 1: capture, stage 2: calculate, done. That's how it worked for our projection, at least.

Well, you could capture once over a range of inputs to get a much better initial first guess too!

I'd bet that they do some of that, too, but if you've got 100 images you want to get "perfect", it's probably faster to capture 10 of them uncalibrated, guess at the curve, capture those same 10 and 10 more calibrated with guess #1, and make a second guess, for a couple iterations than it is to capture all 100 images before any calibration and then all 100 again afterwards to confim, especially if there's any slop in the calibration curve.

Re: TV backlight compensation (2020)

#118

Post by kasabali »

1-6 wrote: post #83
dmos62 wrote: post #78

Pretty cool, but you could instead replace the LEDs.

Sourcing the LEDs, disassembling the panel, and re-soldering each LED is not scalable. The solution mentioned in this article can be open-sourced and distributed to the masses.

Leds are sold as plug in bars. there's no soldering involved. taking out the panel safely is tricky, though.

Re: TV backlight compensation (2020)

#119

Post by astrange »

empiricus wrote: post #20
Candas1 wrote: post #10

Earlier quoted context omitted.

OLED TV's try to prevent burn in, I am not sure it can compensate burn in

I don't see how the TV can compensate for the burnin without having an external picture of the screen. I have a couple of years old OLED TV, and it has burn in... The Netflix logo, the netflix animation, and subtitles are quite visible all the time now. This is despite running periodically the TV pixel refresh or however it is called...

It has a memory of the history of what’s displayed on screen and uses that to predict what’s burned in. This can obviously be a privacy issue, so there’s a trade off in making it too exact.

Re: TV backlight compensation (2020)

#120

Post by bombcar »

londons_explore wrote: post #81
jcims wrote: post #73

Earlier quoted context omitted.

What's the odds that such an obscure problem happens to someone with the patience and wherewithal to figure it out *and* fix it? Pretty impressive.

I did consider replacing the screen, but the only source I could find was China with 60 day delivery by boat, and I decided to find a workaround till the screen arrived... The screens now arrived, but the workaround is so good I can't be bothered to fit it.

It’d be wonderful if we were in a world where working things like this out was worthwhile. I shudder to think how many perfectly working monitors are dumped each year, let alone ones with problems like this.
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