Doom9's Forum - View Single Post - madVR - high quality video renderer (GPU assisted)

jasonwc18 · 15th December 2019, 04:39

I discovered a very strange issue and solved it almost by accident. About a week back, Windows decided to upgrade my NVIDIA driver even though I have Windows set not to upgrade drivers. I used DDU to remove the driver and install my preferred driver. I decided to check the calibration with Calman to make sure everything was fine. I have a JVC RS600 and a Stewart StudioTek 130 display. I use Calman to calibrate my projector/screen manually using the madvr pattern generator. I had calibrated Gamma, RGB tracking manually to an average of below 1 DeltaE (StudioTek 130 screen material has excellent color accuracy and the JVC projector was around DeltaE 2 out of the box with this screen; avg Gamma and RGB tracking well below 1 after manual calibration). Yet, color sweeps were showing me DeltaE errors of 10 for Blue and Cyan. I had seen this once before (identical results) when the Nvidia driver was set to manage color settings rather than the application. However, this time, the driver setting was set correctly.

I repeatedly used DDU with different driver versions, tested different settings in Calman etc. Nothing worked. Finally, I decided to change the color from 12 bit to 8 bit (I normally play in 4K23/RGB/12 bit color). Ran Calman again and both Blue and Cyan had a DeltaE error of 0.5...

I have madvr set to dither the output to 10 bit as the JVC RS600 supports 12 bit color at every level from input to display. Also, I'm pretty sure I've calibrated with 12 bit color in the past without issue. I don't know if this is a Windows issue or a madvr issue (I'm using the latest beta for HDR tonemapping). I don't see how it can be an Nvidia driver issue (unless it's an interaction with a recent Windows update) as this is a build from November 2017 that I've used for ages. Has anyone seen this before?

Also, I'm pretty sure it's not actually impacting normal playback because colors look fine when using madvr to output movies and TV shows on my projector. Given that I saw the exact same behavior and calibration results when I had the Nvidia driver set to manage color, I wonder if Windows is somehow messing with the output in the same way. Very strange and I was just wondering if anyone else ran into this.

15th December 2019, 04:39	#58176 \| Link
jasonwc18 Registered User Join Date: Jan 2018 Posts: 20	Any reason 12 bit color output would result in incorrect colors? I discovered a very strange issue and solved it almost by accident. About a week back, Windows decided to upgrade my NVIDIA driver even though I have Windows set not to upgrade drivers. I used DDU to remove the driver and install my preferred driver. I decided to check the calibration with Calman to make sure everything was fine. I have a JVC RS600 and a Stewart StudioTek 130 display. I use Calman to calibrate my projector/screen manually using the madvr pattern generator. I had calibrated Gamma, RGB tracking manually to an average of below 1 DeltaE (StudioTek 130 screen material has excellent color accuracy and the JVC projector was around DeltaE 2 out of the box with this screen; avg Gamma and RGB tracking well below 1 after manual calibration). Yet, color sweeps were showing me DeltaE errors of 10 for Blue and Cyan. I had seen this once before (identical results) when the Nvidia driver was set to manage color settings rather than the application. However, this time, the driver setting was set correctly. I repeatedly used DDU with different driver versions, tested different settings in Calman etc. Nothing worked. Finally, I decided to change the color from 12 bit to 8 bit (I normally play in 4K23/RGB/12 bit color). Ran Calman again and both Blue and Cyan had a DeltaE error of 0.5... I have madvr set to dither the output to 10 bit as the JVC RS600 supports 12 bit color at every level from input to display. Also, I'm pretty sure I've calibrated with 12 bit color in the past without issue. I don't know if this is a Windows issue or a madvr issue (I'm using the latest beta for HDR tonemapping). I don't see how it can be an Nvidia driver issue (unless it's an interaction with a recent Windows update) as this is a build from November 2017 that I've used for ages. Has anyone seen this before? Also, I'm pretty sure it's not actually impacting normal playback because colors look fine when using madvr to output movies and TV shows on my projector. Given that I saw the exact same behavior and calibration results when I had the Nvidia driver set to manage color, I wonder if Windows is somehow messing with the output in the same way. Very strange and I was just wondering if anyone else ran into this. Last edited by jasonwc18; 15th December 2019 at 04:42.