Local dimming algorithm ruining text clarity on the QN90B

GuardianGI

n00b
Joined
Aug 7, 2017
Messages
12
All fine white text becomes slightly jagged around gray/black backgrounds and that's because for some reason the QN90B local dimming algorithm crushes whites/light grays together thus breaking grayscale text rendering which relies on different tones of gray to make the text look less aliased. This seems to affect all picture modes. Putting up a large white element/window in the corner or around the crushed text to boost the local dimming brightness fixes the issue as the text regains its grays/whites for grayscale rendering to work.

Weirdly I tried searching for the problem on reddit/avsforums/google and nobody seems to notice this problem.

I read about the pixel interference problem on the 43 panels but this affects all the panel, not just top or bottom.

I might take some pictures later if anyone cares.
 

pendragon1

Extremely [H]
Joined
Oct 7, 2000
Messages
42,864
All fine white text becomes slightly jagged around gray/black backgrounds and that's because for some reason the QN90B local dimming algorithm crushes whites/light grays together thus breaking grayscale text rendering which relies on different tones of gray to make the text look less aliased. This seems to affect all picture modes. Putting up a large white element/window in the corner or around the crushed text to boost the local dimming brightness fixes the issue as the text regains its grays/whites for grayscale rendering to work.

Weirdly I tried searching for the problem on reddit/avsforums/google and nobody seems to notice this problem.

I read about the pixel interference problem on the 43 panels but this affects all the panel, not just top or bottom.

I might take some pictures later if anyone cares.
firmware up to date? my hisense added a text mode to help.
 

GuardianGI

n00b
Joined
Aug 7, 2017
Messages
12
1304.1 firmware, all up to date

Here is the image around black background, notice how the hexagon border becomes darker inside the color-crushed area compared to the hexagon's interior which means the local dimming algorithm doesn't just crush colors it also inverts lighter colors to become darker than the surrounding colors
crushedinverted.jpg


And this is when I put a white window next to the element to lessen local dimming, which fixes the color crush and inversion. Notice the hexagon borders becoming uniform and lighter instead of being inverted:


fixed.jpg
 
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GuardianGI

n00b
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Aug 7, 2017
Messages
12
More good news from rtings about 43 QN90B:
  1. Updated Sep 16, 2022: We confirmed that VRR doesn't work properly when sent a 120Hz signal from a PC.
With LD algorithm also crushing colors/whites and breaking text clarity I'm really glad I bought this as a monitor :)

Also I noticed that rtings gave this TV the worst viewing angle rating of any monitor. It's like Samsung intentionally sabotaged the 43 version so as to not compete with their gaming monitor lineup too much.

Hope Sony produces a 43 inch mini-led next year so I can sell this TV off.
 
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Senn

Limp Gawd
Joined
Jul 29, 2021
Messages
214
Also I noticed that rtings gave this TV the worst viewing angle rating of any monitor.

Given that the 43" 90B appears to use the same panel as all current equivalent size "gaming" monitors (due to the pixel interference issue being identical) and my experience with the FV43U's viewing angle being dire, I'm not wholly surprised at this.

I refuse to touch any 43" LCD until it's confirmed that they've finally moved away from that awful flawed panel. My 50" QN94A is big, perhaps too big. I'm willing to live with that to get away from the annoyances of the 43" panels though.

Regarding the LD, how important is local dimming to you for PC use? I use my monitor on the PC for work more than I do gaming so I've actually turned the local dimming off for PC mode in the service menu. It's not ideal as it basically defeats the purpose of mini LED and HDR is basically impossible. But for 4k SDR, the image quality and colour rendition are far more consistent than allowing the LD algorithm to have its way with desktop applications. I'd only recommend this if gaming/HDR is not a priority. Note that I have a PS5 for gaming, it switches the LD back on when moving to that input.
 
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