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[Mystery solved] HDR monitor disables local dimming with FreeSync ON - artifacts, banding and darker colour problems in HDR ("HDR Gaming" mode)


#1

[Now I at least know why it happens, see my newest post]
Monitor: HP Pavilion Gaming HDR 32 (VESA HDR 600 certified, FreeSync over DisplayPort support)
GPU: GTX 1070, 418.81 driver (latest)
OS: Latest Windows 10 64bit
Monitor suffers from terrible artifacting, but only in “HDR Gaming - Freesync” mode (I want to use it, because it only supports FreeSync). Dark colours become completely black and there are lots of artifacts around slightly less dark ones. Problem with HDR turned on in Windows persists with FreeSync both off and on, 60 and 75 FPS. Everything is fine in “VESA 600” and “HDR Video” mode.
My best guess is monitor in problematic mode identifies itself as HDR 1000 not HDR 600, because in Assassin’s Creed Odyssey I can set maximum HDR brightness, and reducing it from 1000 gets the image darker. This would explain why I am loosing shades of gray.
This looks like a software problem. I would be very grateful for any help!!



#2

What monitor, what GPU, and how are they connected?


#3

Sorry, how could I had forgot!


#4

I figured it out! This is a very interesting behaviour for lower end HDR monitors and it might help others with troubleshooting.
Local dimming is disabled in “HDR gaming - FreeSync” mode! It adjusts backlight backlight in zones, so it greatly improves contrast for HDR and is necessary for HDR 600 standart this monitor is certified for. So basicially with FreeSync enabled our monitor becomes HDR 400 instead of HDR 600. If it notified the system and GPU about that, it would just displayed a bit worse image. But it doesn’t, so it has to squish higher dynamic range to a smaller one, as without local dimming it can’t get parts of the monitor as bright and as dark. This is why there are artifacts, washed out colours and loss of dark details.

So this is not a problem with my monitor, but a design decision, as it probably would be way harder for the monitor to both controll the backlight so precisely and adapt the refresh rate. So I get why HP did that.

But anyways, this is not what I paid for! In the description this was VESA HDR 600 certified and FreeSync monitor. And I can get either that HDR range in “VESA HDR 600” mode, or FreeSync working and broken and lower pec HDR in “HDR Gaming - FreeSync” mode. I would be completely fine with that, if it was stated anywhere in the description.
I am going to keep this monitor, because the colours and contrast are amazing, and it is way cheaper in Poland than any other HDR monitor, but I already contacted HP to fix the description, and the shop for partial refund. I will see what comes out of this.


#5

I suppose you have to look for FreeSync 2 monitor as that has HDR 600 as min requirement, and great that you posted this thing because its first I’m reading about that problem