Uneven banding in fullscreen HDR output with R10G10B10A2 swapchain

Gaming and Visualization Technologies APIs DirectX, DXR, DirectCompute
1

Hi there,

I am working on HDR output support in the Godot game engine and have come across an unexpected behaviour in NVIDIA Windows drivers that I cannot reproduce with other GPU drivers, such as AMD integrated graphics or Intel integrated graphics.

Initially I believed this issue might be better posted in the drivers category, but after more testing I have found that this issue seems to be specific to DXGI swapchains; I am not able to reproduce the same severity of banding with a Vulkan HDR swapchain using equivalent configurations.

The issue that I am experiencing can be reproduced using an unmodified version of Microsoft’s D3D12 HDR output sample project. To reproduce the issue:

  1. Use a high-quality HDR monitor that supports 10-bit full range RGB, such as the Asus PA32UCDM
  2. Ensure HDMI output to the monitor is full range RGB, 10-bit HDR
  3. Run the sample project
  4. Press spacebar to enter full screen mode and use Pg Up / Pg Down to compare DXGI_FORMAT_R10G10B10A2_UNORM and DXGI_FORMAT_R16G16B16A16_FLOAT
  5. Note that uneven banding that is not related to 10-bit quantization is visible on the gradients with DXGI_FORMAT_R10G10B10A2_UNORM
  6. Press spacebar to leave full screen mode
  7. Note that the uneven banding is no longer visible, no matter what size the window is

I have also created a modified version of this sample project that makes the issue more visible. This modified version can be found here: GitHub - allenwp/DirectX-Graphics-Samples at banding-test-pattern

The following image shows eight photos of different swapchain formats with NVIDIA Intel, and AMD drivers, showing that the issue is specific to NVIDIA drivers:

nvidia-unexpected-hdr-banding-intel-amd
nvidia-unexpected-hdr-banding-intel-amd1853×1480 460 KB

I have reproduced this issue on two different computers with Windows 11 Pro Version 10.0.26100 Build 26100 with an NVIDIA GeForce RTX 5070 Ti with these driver versions:

Game ready: 581.08 and 577.0
Studio: 580.97

Some more notes:

  • Before installing these drivers, I have tried running CleanupTool_1.0.20.0.exe as an administrator and rebooted. https://developer.nvidia.com/cleanup-tool
  • Enabling Debug Mode from the NVIDIA control pannel does not change the behaviour
  • I am not aware of any overlays that may be running on my computer (NVIDIA Experience/App is not installed and Discord/Steam/etc are not running)

Thanks for your help,
Allen

2

banding with the dxgi R10G10B10A2 format means your gamma curve is wrong.

set the driver to reference mode.

3

Thanks for the suggestion, @Sora; I hadn’t tried reference mode yet.

Unfortunately, enabling “Override to reference mode” in the Desktop Colour Settings did not have any impact on this behaviour: even with reference mode enabled, the uneven banding is visible just the same as when reference mode is disabled.