Reproduction steps:
1. Open the attached “IN-48797 HDR Splashscreen.zip“ project
2. Make sure that the project is running in the Direct3D12 API (for testing HDR in the Editor)
3. Open the “OutdoorsScene”
4. In the Player settings, in “Other Settings”, make sure “Allow HDR Display Output” is enabled and “Swap Chain Bit Depth” is set to “Bit Depth 16”
5. In the “Splash Image” category, press the “Preview” button
6. Observe the Game view

Expected result: The colours and brightness of the Splash Image are identical to the same image displayed after the SplashScreen has finished fading out
Actual result: The Splash Image appears to be darker than the same image displayed after the SplashScreen has finished fading out

Reproducible with: 2022.3.7f1, 2023.1.9f1, 2023.2.0b5 (DX11, DX12)
Could not test with: 2021.3.29f1 (HDR did not apply to any HDR images tested)

Reproduced on: Windows 11 Pro 22H2, macOS 14.0 Darwin 23.0.0 (by the user)
Not reproduced on: No other environment tested

Notes:
- In the user’s case, they experienced overly saturated colours on the Splash Image instead of darker ones (see user-attached “mac_wrong_color_space.mov” video)
- Reproducible in a new project with any HDR image
- Reproducible in Player
- HDR Editor in DX11 is not supported but still reproduces the issue in the Player
- Could not test with Vulkan API (Swap chain with supported HDR formats not found. Using supported SDR swap chain format)
- Monitors used: Alienware m15 R3 internal OLED HDR display and Samsung Odyssey G9 in HDR mode