2020 QLED T models (Q80T, Q90T, Q800T, Q900T) HDR game mode brightness / local dimming bug

[Rauttis]

I bought a Q80T a couple of days ago and have noticed a really annoying issue when using the tv with the combination of HDR and game mode.

I'm fairly certain this is a software bug in the TV since I can reproduce this issue with 100% accuracy, and it happens on the dot at the same moment every time. It's basically on a timer.

Basically when the game is displaying a HDR signal and game mode is enabled, exactly after 6 minutes the brightness of the TV suddenly drops by around 20 (50 -> 30). The value of brightness setting doesn't actually change however. Messing with the brightness setting does not restore the brightness to it's original state, but changing the local dimming setting from standard to low and then back to standard does. Switching game mode off and then back on also fixes the issue, but then it happens again EXACTLY after 6 minutes (I've timed this with a stopwatch).

Has anyone else experienced this issue? Or can someone maybe test this on their TV to see if you can reproduce it?

Exact repro steps on how I can reproduce this 100% of the time on the PS4 Pro:

1. Set brightness to max (50)
2. Set local dimming to standard (bug happens on high as well)
3. Enable game mode
4. Turn off game motion plus
5. Turn off intelligent mode and all the brightness related settings in eco settings, as these can influence the brightness level of the tv.
6. Launch a game that runs in HDR
7. Start your stopwatch
8. Do whatever you want in the game or you can also go back to PS4 menus, find a bright scene where you can notice a brightness drop easily
9. When the stopwatch hits 6 minutes, you should see the TVs brightness suddenly drop by a large amount. By eye the brightness drop seems about equal to dropping the brightness from 50 -> 30 by hand.
10. Go to picture settings and set local dimming to low (brightness does not change)
11. Set local dimming back to standard (brightness suddenly jumps to the original level. Brightness can be restored by switching input away and back as well, or by disabling and re-enabling game mode)
12. And again after EXACTLY 6 minutes the bug again repeats and the brightness drops down again

Some other notes: The PS4 has a screensaver that basically dims the screen if it is idle for a while. This is not the cause of this, this happens even when the console is in active use and the brightness can be restored temporarily by changing the local dimming setting like described above. I have not managed to reproduce this issue with game mode off, so it seems to be related to game mode.

Software version: 1304

[Muzzakus]

Hi Olmaz,

Further testing in Movie mode reveals inverse ghosting is also preset in this mode. Have tested with motion interpolation on and off, inverse ghosting is visible irrispective off interpolation setting in Movie mode. Used COD Modern Warefare on the St Petrograd as my baseline test.

In summary Inverse Ghosting (or atlease below noticable threashold) is only absent in Game Mode with Game Motion off.

What a ***** show. Are you able to provide a link to your Youtube test video for our comparison? Much appreciated.

[Danmay]

I have learnt a few interesting things. It seems to me all the issues are down to how the TV deals with the incoming FPS of the source.

On the Xbox you can change the video output from 'automatic' to either manual HDMI or DVI. If you change to HDMI, the screen defaults to 640p 60HZ, and disables HDR. Oddly, in this configuration, setting the TV to 1080p 120 mode does some magic things. Any sign of scrolling lines for me was gone, nothing. Additionally, the pixel overdrive seemed well tuned with minimal smearing and overshoot. In this mode however, the xbox doesn't allow you to enable 4k, and you get the message 'Your TV doesn't support this resolution'...

In conclusion, I have no idea how this TVs software works in relation to gaming devices.

[Suriya]

This thread is leading somewhere not related to the topic. 

Good bye. 

[Luke_H]

Completely agree. I found this super useful initially with all the useful information being shared, and in a way which wasn't childish or nasty. Im sure there are indeed some Trolls in here, why?? Thats beyond me, clearly to much time..... To save me having to trawl through all the rubbish that isnt relevant am i right in thinking a firmware has been released that address the original dimming issue in game mode? And this is currently only available for download to USB? 

Im in the UK with the 65" Q80T.... 

And please give it a rest with all the other pointless rubbish guys!!!

[Toejo78]

Yeah the latest firmware fixes the dimming issue.

[Toejo78]

If you are suffering from VRR HDR dark imagine there's a work around for that too.

Set local dimming to High 

Contrast Enhancer to High 

Gamma should be on ST.2084 anyway with HDR but you need to move ".ST.2084 " bar to 3

This gives you the same brightness as if VRR was off.

I agree with this threat is getting full of *****s ruining it for people wanting solutions. As the original bug is fixed this should be closed and new topics opened for other problems.

[BogaMoge]

Hi Muzzakus,

Just let you know that I had opened a thread about this problem a few weeks before, you can find it here (the video I used is there too).

Q90T/Q95T : Inverse Ghosting while playing a game in Movie Mode

Maybe you can copy paste your posts too so they are all at the same place, and we can have a thread dedicated to that problem, since you are the first one I've talked to that acknowledges it the same way I do.

[BogaMoge]

Hi Danmay,

First : maybe a stupid question, but how do you set up the tv resolution and refresh rate? I haven't found any settings for that, it just changes automatically...

Second : Just let you know that I had opened a thread about this problem a few weeks before, you can find it here :

Q90T/Q95T : Inverse Ghosting while playing a game in Movie Mode

Maybe you can copy paste your post too so they are all at the same place, and we can have a thread dedicated to that problem, since you seem to encounter the same problem as me.

[Danmay]

Hello there,

You cannot change the resolution and refresh rate at tv end, this is done by the device. When you change the refresh rate and resolution on the device, the screen will go black, and come back on at the new setting.

What's strange about the TV is the way it deals with various resolution/framerates in regards to the faint scrolling lines that are present.

[BogaMoge]

Thank you for opening the thread. I have the same problem in Game Mode : extremely bad local dimming (and even more noticeable in HDR).