LG34UM95-P and Terragen

Started by WAS, March 21, 2020, 05:24:42 pm

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I got this ultrawide 4k IPS display and having issues with it. If I turn the display off, it seems TGs RenderMan will start throwing errors and give me black buckets here and there, and other applications crash as well with "breaking point reached". I have tried looking up the monitor and any issues but can't find anything related.

I did find out I'm at 8bpc color depth for some reason, not 10bpc like the monitor advertises, and I'm at native aspect ratio and resolution, with drivers installed.

I notice I don't have the cable installed that connects via USB (ordered one) for LG TrueColor software, which I guess dynamically adjusts the color on the fly. Maybe that's why my color is limited.

Has anyone had this monitor and any issues rendering or shutting it off? I have seen no issues while the monitor is on..just when I turn it off for the night.

I have 32gb RAM and TG idle is using 2gb and renders seem to be peaking at 4gb so don't think that's related. Haven't populated any scenes yet.

None of this was a issue on my Samsung HD 1080p monitor. :/


Regarding the Power Off problems - no idea, sorry.

Regarding bit depth I have a few:

Windows or Mac?
What graphics adapter do you have? Does it support 10bit output?
Is the Monitor connected via Display Port? Neither Thunderbolt nor HDMI does support 10bit, afaik.

Is the monitor a real 10bit display or does it use 8-bit+FRC (Frame Rate Control)?

"It is also worth mentioning there are some monitors advertised as offering 10-bit color output, but are not true 10-bit, but rather 8-bit+FRC. 8-bit+FRC (Frame Rate Control) monitors are 8-bit monitors that essentially fake the output of a 10-bit monitor by flashing two colors quickly to give the illusion of the color that should be displayed if it were a true 10-bit monitor. For example if the color that should be displayed on the 10-bit monitor is number 101 in the Look Up Table (LUT), and an 8-bit monitor is only capable of displaying color number 100, or 104, an 8-bit+FRC monitor would flash the color number 100 and number 104 quickly enough that in theory one should not notice the flashing. It's goal is to fake the human eye into thinking it is really color number 101. To do this the 8-bit+FRC monitor would flash between color number 100 for 75% of the time, and color 104 for 25% of the time, to give the illusion of color number 101, similar to how rapid succession still shots work to give the illusion of motion when displayed one after the other quickly enough. If color 102 needed to be displayed, an 8-bit+FRC monitor would flash between displaying color number 100 for 50% of the time, and color number 104 for 50% of the time to give the illusion of color 102, as opposed to a true 10-bit monitor which would be able to simply display color number 102 from the LUT."


Turning True Color Finder on recalls the hardware calibration settings done by LG.
The True Color Finder software only works with a hardware calibrator device if you want to recalibrate, I think.
If you have not purchased one of those which are supported by the software it is pretty useless.
But i could be entirely wrong about that.

Using adapterslike dvi-hdmi or dvi to display port may cause issues.
I think the USB Port simply works as a hub.

Hth. CHeers, Klaus
/ ASUS WS Mainboard / Dual XEON E5-2640v3 / 64GB RAM / NVIDIA GeForce GTX 1070 TI / Win7 Ultimate


The monitor has its own tuner build in for the True Color but you need to have USB connected. 

It is connected via HDMI so I guess that's the issue than, though my RX 580 was set to 10bpc. It's now 8bpc with no 10bpc available. Even 6bpc disappeared. 

The color dial for TG, for example, has terrible banding and is not smooth at all. Colours in the saturation/darkness picker of the color wheel also look off. It's a shame. If the cable I was missing that came with it doesn't help than may just go back to old display. At least color was totally smooth by eyesight.


Here is the monitors specs for reference. Not familiar with these class displays at all. Still I'm the sh** your pants phase seeing HDR 4K displays. Lol


One thing I notice though is at native 4K I only get 50hz, not 60hz, and GPU seems to support 4k 60hz  so that interesting variation between specs.