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TV backlight compensation (2020)

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Re: TV backlight compensation (2020)

#81

Post by londons_explore »

jcims wrote: post #73
londons_explore wrote: post #47

Earlier quoted context omitted.

I noticed the screen only died when playing videos and always died at the same point if I rewatched a video. Notably, greyscale videos never caused the issue. Then I went through a video frame by frame to get to the frame it died on. Then I erased parts of the frame to find which part caused it. Eventually I found that if the red or blue pixel in the 481st column and the green pixel in the 482nd column have a differe…

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.

Re: TV backlight compensation (2020)

#82

Post by 1-6 »

This technique is cool but it seems like it would cause poorly performing pixels to get worse over time.

Would it be possible to create an inverted image that would correct the backlight by burning in the bright areas? It would seem like a more difficult task to accomplish because pixel burn-in time is a variable that’s hard to measure.

Re: TV backlight compensation (2020)

#83

Post by 1-6 »

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.

Re: TV backlight compensation (2020)

#84

Post by t4h4 »

infomax wrote: post #40

I have the same idea each time I read something about backlights; How easy would be to place a cheap LCD at the back of the main screen and mirror the same output (in horizontally inverted mode)? Technically it might require synchronizing the frame latency differences between the two devices, but would such a hack improve the perceived quality?

Hisense Dual Cell might be what you're talking about.

Re: TV backlight compensation (2020)

#85

Post by Tade0 »

I damaged my laptop's screen by leaving it running at 100% CPU with the lid closed for too long(not my intent - that was "sleep mode"). The adhesive keeping the LCD layers came off, creating a diagonal striped clouding pattern.

I was meaning to do something similar to the author[0], but couldn't make time and just used this opportunity to buy an external screen.

I'm glad someone put in the work so that now I may be able to use my original screen again.

[0] My most desperate idea was to run a RDP session locally and process the displayed image. Seemed simpler than trying to modify the content of the screen directly.

Re: TV backlight compensation (2020)

#86

Post by ermir »

sorenjan wrote: post #66

This reminds me of the world cup in South Africa, where the spectators used vuvuzelas to make a unique sound that I found hard to endure. I figured it would be easy to use a notch filter to remove it, but I could never find a way to implement it it real or near real time, only as post processing.

I remember the broadcasters also implemented this solution straight into the stream, the TV spectators did not have to do anything.

Re: TV backlight compensation (2020)

#87

Post by MrBuddyCasino »

dmos62 wrote: post #78

Pretty cool, but you could instead replace the LEDs.

I did this once, was pretty easy. The backlight color had turned completely blue. The strips can be bought as spare parts and swapped easily without any soldering. The hard part is finding out the parts number of the LED strip for the particular TV.

Re: TV backlight compensation (2020)

#88

Post by jabroni_salad »

BoorishBears wrote: post #36
ifqwz wrote: post #27

The quality of computer monitors is appalling - after buying and returning several monitors because of quality issues, I briefly considered doing this system-wide to fix colour uniformity problems. Eventually I chose to keep my old monitor instead. It has uniformity problems as well but it doesn't cost me $1000 extra to keep. But it's a damn shame that you can't throw enough money at manufacturers to make them make m…

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…

Gamers hit up blurbusters to see how the motion is and it either looks okay or you get a headache. The OEMs optimize for that (hence the focus on g2g and adaptive sync) and then just jack up the saturation slider to compensate for everything else.

And hey, those wasabis and catleaps got you a 1440p IPS panel that did 90% of what you want for 50% of the price at a time when 1440p and IPS was still kind of rare to own. Most people who got one were upgrading from a typical TN so even a crappy IPS looks good in comparison. I was playing eve online at the time and caused at least 10 people in my corp to buy them when they saw how much screen estate you got at a higher res.

Re: TV backlight compensation (2020)

#89

Post by dylan604 »

Tade0 wrote: post #85

I damaged my laptop's screen by leaving it running at 100% CPU with the lid closed for too long(not my intent - that was "sleep mode"). The adhesive keeping the LCD layers came off, creating a diagonal striped clouding pattern. I was meaning to do something similar to the author[0], but couldn't make time and just used this opportunity to buy an external screen. I'm glad someone put in the work so that now I may be a…

>The adhesive keeping the LCD layers came off, creating a diagonal striped clouding pattern.

now this sounds like something my younger me would be interested in seeing. what kind of special effect look can you get from that by running different colors/patterns through that stripe? obviously, the only way to make it usable would be to record the screen externally, but it would not be the first time someone (ahem,me) pointed a camera at a screen for sfx/vfx. back in the old analog days, i would by crts specifically because of their "issues".

Re: TV backlight compensation (2020)

#90

Post by adrian_b »

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…

I use a pair of Dell monitors with IPS screens (U2720Q and UP2414Q).

I always use as background a solid grey (#808080) and there is no noticeable non-uniformity.

I have tried now your color (#FF6400) on the U2720Q. Because this color is much brighter, if you look carefully you can see that there are small areas at the corners, especially at the 2 lower corners, with lower brightness. Also the 2 lateral edges have a slightly lower brightness, but the difference from the center is less visible than for the 2 lower corners.

However the areas affected are small (maybe a width of about 1/30 or 1/40 of the screen width) and you really have to look with the intention to find non-uniformities. When looking casually at the screen there is no obvious non-uniformity.

For emissive displays like CRT or OLED it is easier to achieve uniform brightness over the screen.

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