HDR display question

When using the BP node “Supports HDR Display output”, what exactly is it checking for to determine wheather or not the “system” supports HDR display output?
Does it examine the machines at work or does it simply determine if the project itself is fit for HDR?

It checks the system.

But what exactly qualifies as the system in this instance? I can think of several things that could, the monitor, the computer, the operating system and the project file itself.

Mostly the video card I should think.

Hello. If you’re into technical stuff, I highly recommend getting access to UE4 code. I’m a technical artist and normally don’t touch the code, but since I set up Visual Studio and configured it for our project, my life became SO much easier, especially when dealing with GameUserSettings stuff like HDR, Scalability etc. I must say some of this stuff is broken as far as I can tell (I submitted a few bugs), or sometimes it just doesn’t work as you think it would, so the ability to double click a native BP node and have it opened in VS is life-saving (or if this doesn’t work, you can always find it manually). So ask your programmers how to set this up (basically download free VS, configure it according to the UE doc, right click on your project file to create a Solution, oh, and your engine install should have the Editor Symbols For Debugging component enabled - you can change it in Epic Launcher), or if your project is not code-based, then maybe you could look the code up on GitHub, or just create an empty C++ project…

Anyway, this way I was able to find that the SupportsHDRDisplayOutput() function returns the GRHISupportsHDROutput variable value, which is set differently on different platforms, but for WindowsD3D12 it is set to whatever SupportsHDROutput() returns, which looks like this:

static bool SupportsHDROutput(FD3D12DynamicRHI* D3DRHI)
// Determines if any displays support HDR
check(D3DRHI && D3DRHI->GetNumAdapters() >= 1);

bool bSupportsHDROutput = false;
const int32 NumAdapters = D3DRHI->GetNumAdapters();
for (int32 AdapterIndex = 0; AdapterIndex < NumAdapters; ++AdapterIndex)
FD3D12Adapter& Adapter = D3DRHI->GetAdapter(AdapterIndex);
IDXGIAdapter* DXGIAdapter = Adapter.GetAdapter();

for (uint32 DisplayIndex = 0; true; ++DisplayIndex)
TRefCountPtr<IDXGIOutput> DXGIOutput;
if (S_OK != DXGIAdapter->EnumOutputs(DisplayIndex, DXGIOutput.GetInitReference()))

TRefCountPtr<IDXGIOutput6> Output6;
if (SUCCEEDED(DXGIOutput->QueryInterface(IID_PPV_ARGS(Output6.GetInitReference()))))

// Check for HDR support on the display.
const bool bDisplaySupportsHDROutput = (OutputDesc.ColorSpace == DXGI_COLOR_SPACE_RGB_FULL_G2084_NONE_P2020);
if (bDisplaySupportsHDROutput)
UE_LOG(LogD3D12RHI, Log, TEXT("HDR output is supported on adapter %i, display %u:"), AdapterIndex, DisplayIndex);
UE_LOG(LogD3D12RHI, Log, TEXT("		MinLuminance = %f"), OutputDesc.MinLuminance);
UE_LOG(LogD3D12RHI, Log, TEXT("		MaxLuminance = %f"), OutputDesc.MaxLuminance);
UE_LOG(LogD3D12RHI, Log, TEXT("		MaxFullFrameLuminance = %f"), OutputDesc.MaxFullFrameLuminance);

bSupportsHDROutput = true;

return bSupportsHDROutput;

Also, when I was implementing this feature, only through code I found that r.AllowHDR needs to be set to 1 (e.g. in DefaultEngine.ini) for HDR to work. I really wish this stuff was better documented…

Hi. I´m trying to set up Unreal for working in HDR. I´m using the commands that is in the documentation, like r.AllowHDR. But i´m getting an error it says:
Error: r.AllowHDR is read only!

So, i cannot change the value from 0 to 1. How can i change it? I cannot find this in any DefaultEngine.ini.

I just added it to DefaultEngine.ini under the [/Script/Engine.RendererSettings] section.

Thanks. I´ve been able to change the parameter to 1. But i cannot make it looks good on the screen. In the documentation it says:

" Once you’ve setup the Blueprint or C++ call for GameUserSettings, you can run any cooked project, use the command line argument -game mode , use Standalone game mode, or Play-in-Editor (PIE) in a new window using exclusive fullscreen (press Alt + Enter or use the command fullscreen from the console window)."

For example in standalone mode in full screen it is totally black. In PIE, when i try to go full screen with Alt+Enter it goes back to the UI. The HDR mode in windows is activated. And games like MSFS2020 is running really well in HDR.
Is there any place with good info about how to set up everything and render it out in HDR?
Maybe i could ask these guys how they made it: Unreal Engine 4 | Infiltrator | 4K60p HDR 10 - YouTube