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Glossary:High dynamic range (HDR)

From PCGamingWiki, the wiki about fixing PC games
Illustration of the difference between SDR and HDR
Illustration of the difference between SDR and HDR

For a list of games, see games with high dynamic range support.

Key points

Expanded dynamic range allows for more vibrant colors and greater contrast in supported games on HDR-compatible displays.
Support is still low; new games are not guaranteed to support it, wrappers/injectors/overlays without support will look bland and washed out in HDR mode, and tools/features without support won't function properly, such as the inability to capture screenshots using Steam in HDR mode.[1]
Some games might support HDR output, but not actually render the game internally in high dynamic range (see HDR rendering), instead merely just rebalances the final SDR rendered image onto a higher dynamic range. This is sometimes referred to as "fake" HDR.

General information

High-dynamic-range video
DisplayHDR and certified products
In-depth UHDTV (HDR and WCG) explanation

HDR output on an HDR display

This is the modern definition of "HDR" in relation to gaming after the arrival of HDR output compatible TVs and monitors in the 2010s.

High Dynamic Range output or High Dynamic Range is a technology that first and foremost enables a screen to display an image at a much greater range of contrast. In practice this usually goes hand in hand with an increased color bit depth from standard 8-bits per color to 10-bits per color or more. In any case, both the software, graphics card (incl. driver), connection and display need to support this technology in order to actually be able to put a HDR image onto a HDR display. For games to fully make use of the expanded dynamic range available on a HDR display, HDR rendering needs to be taken advantage of in the render pipeline of the game, and afterwards the rendered HDR content needs to be output in a HDR display compatible range as well.

It is possible for games not rendering in HDR to "fake" supporting HDR output on a HDR display by rebalancing the brightness of the final SDR rendered image over to a higher dynamic range; meaning the game and final image output will not actually take full take advantage of the additional range available. Further on, as the HDR mode of most displays is designed around proper HDR content, this can also result in a somewhat degraded visual experience compared to using the SDR mode of the same display, which is designed around showing SDR content in the best possible way.

Windows 10 v1803 ("April Update") and later includes automatic brightness balancing of all standard dynamic range content on a HDR display when HDR mode is enabled in the operating system, effectively rebalancing their content against proper HDR content. This feature was added to prevent SDR content from looking dim (greyed/washed out) when displayed in HDR mode, as occurred in previous versions. The operating system allows the brightness for SDR content to be configured under Display settings > Windows HD colors > HDR/SDR brightness balance. Consequently, all games lacking proper HDR output and running in window mode (both regular and borderless) will automatically have their SDR brightness balanced to the higher dynamic range when HDR mode is enabled on a HDR display. Disable HDR mode in Windows 10 or run the games in exclusive fullscreen mode (with the fullscreen optimizations of Windows 10 disabled) to allow those games to output their SDR content in the SDR mode of the display.

HDR rendering

This was typically known as "HDR" in relation to gaming in the 2000s before the arrival of HDR output compatible TVs and monitors in the 2010s.

High-dynamic-range rendering at Wikipedia

High-dynamic-range rendering (HDRR, HDR rendering or high-dynamic-range lighting) is the process of generating computer graphics scenes using lighting calculations done in high dynamic range (HDR). This allows preservation of details that may be lost due to limiting contrast ratios, by mimicking the way cameras and even eyes handle light exposure. It is especially helpful when rendering scenes with multi-layer surfaces, especially when the surface is using normal and specular maps or even highly reflective surfaces (like the water), which can not be rendered correctly in standard dynamic range.[2] Another important area where HDR rendering is useful is exceptionally dark or bright areas as well as transitions between them. Using a dynamic tone-mapping, HDR rendering can adjust the exposure of a scene based on the amount of light in it to simulate a camera lens adjusting to the light.[2]

Games rendering in HDR do not necessarily output that image in HDR display compatible range. Due to technical limitations of SDR monitors of the 2000s when HDR rendering became more common, game developers had to map that vastly bigger dynamic range back onto what consumer displays commonly support. Since the introduction of HDR monitors in the second part of the 2010s, games do not have to perform that tone mapping any longer unless the operating system and/or monitor is running in SDR mode. However despite the availability of HDR monitors and inclusion of HDR output in modern versions of Windows, support for HDR output in newer games is still quite uncommon and the majority of games still prefer to map the HDR rendered image onto a standard dynamic range, even if HDR mode is enabled in the operating system.

For games that perform rendering in high dynamic range but do not natively support outputting it in HDR mode, it might be possible to force HDR output through alternative methods.

HDR display certifications

VESA DisplayHDR certified products

For PC users the DisplayHDR certification from VESA is relevant as this certification is designed for and around computer monitors and its use in the PC market. The certification breaks the market down into different segments based on various criteria such as the minimum luminance level, color gamut, and bit depth supported by the monitor.

For typical television displays the Ultra HD Premium certification from the UHD Alliance also exists and is designed around displaying movie and television content on larger displays viewed at a distance. According to the Ultra HD Premium certification, HDR displays must have either a peak brightness of over 1000 cd/m² and a black level less than 0.05 cd/m2 (a contrast ratio of at least 20,000:1) or a peak brightness of over 540 cd/m² and a black level less than 0.0005 cd/m² (a contrast ratio of at least 1,080,000:1).

Support in games

For a list of games, see games with high dynamic range support.

This refers to support in games for providing HDR output on an HDR display. It does not refer to HDR rendering. Games released before 2017 have no support for HDR output, unless it was patched in later or enabled through the use of a third-party mod.
Windows 10 v1703 ("Creators Update") or later as well as a HDR compatible graphics card, connection, and display are required in order to actually be able to show HDR content inside of only a window. Refer to the game-specific articles for details on how to enable HDR support.
Note that Windows 10 v1803 ("April Update") and later performs automatic brightness balancing of SDR content when HDR is enabled, which is not the same as if the game natively supported HDR output. To see if the brightness balancing feature is being used, play around with the Display settings > Windows HD colors > HDR/SDR brightness balance (called SDR content brightness in Windows 11) while the game is running in a window. If the brightness of the game changes then it outputs in SDR and does not support HDR output natively in window mode. However if the brightness does not change then the game properly outputs in HDR.

Enable HDR output in unsupported games

A simplified illustration of how Auto HDR works
A simplified illustration of how Auto HDR works

Some games or engines might support forcing native HDR output through their configuration files:

  • Unreal Engine 4 and Unreal Engine 5 have native HDR output that can be forced in many newer games with mixed results. Earlier versions of the engine requires running in Exclusive Fullscreen (FSE) in order for this to work, while newer versions supports it for windowed modes as well.

For other Windows games or engines lacking native HDR display support it is possible to approximate or retrofit HDR output to achieve a similar result. While some of the methods can technically be used for older APIs lacking HDR rendering support, the best results can be expected from APIs that natively support it (DirectX 9 or OpenGL and above).

Below is the most commonly used methods to achieve HDR output on unsupported games:

Special K

Special K's HDR Retrofit feature works on Windows 10/11 and can retrofit HDR support in most DirectX 11-12 games by forcing a scRGB 16-bit swapchain buffer and undoing the SDR compression of the internal tone mapper of the game with its own user-configurable tone mapper.

  • For native DirectX 11 games Special K supports remastering 8-bit, 10-bit, and 11-bit render passes to further enhance the end result of the HDR retrofit process.
  • HDR retrofit support in DirectX 12 and OpenGL is more limited and can only undo the SDR compression of the internal tone mapper of the game.
  • As of 2022 Special K can also interop OpenGL through DirectX 11, enabling some limited HDR retrofit in such games as well.

RTX HDR

If you have an Nvidia GPU, on Windows 11 you can activate RTX HDR via the NVIDIA App, which works in almost all games (DX9, DX10, DX11, DX12, Vulkan, OpenGL) as long as they are running in fullscreen exclusive or borderless mode. This functions similarly to Windows 11 AutoHDR but has the advantage of upgrading SDR to HDR by using gamma 2.2, instead of sRGB, thus avoiding raised blacks.

RTX HDR is only officially supported on driver 551.52 or later, but can be enabled on earlier driver versions with the NvTrueHDR third-party tool.
RTX HDR supports different quality levels but NVIDIA App only enables the most expensive one, the NvTrueHDR app above can also let you pick quality levels for increased performance, without any noticeable quality difference.
Several hidden settings (such as disabling adaptive brightness) can be changed via the TrueHDRTweaks package available on the NvTrueHDR page.

DXVK with ReShade AutoHDR

This custom DXVK fork can be used to replace game buffers to HDR formats through a config file.
Once the game outputs on an HDR buffer, it's possible to apply custom "AutoHDR" implementations by running ReShade on top of it, for example Pumbo's AutoHDR.

Windows Auto HDR

For a list of games, see games with Auto HDR support.

Windows 11's Auto HDR feature intelligently expand the color/brightness range of DirectX 10/11/12[3] games up to HDR by running a post-process pixel shader pass that "recovers" the color data that has been compressed by modern games' internal tone mappers using a machine learning algorithm. Games with natural/photo realistic lighting styles work well with the algorithm, but some non-photo realistic styles may yield undesirable results.[4]

  • Use the Windows HDR Calibration app for additional optimizations and achieve a better experience.[5]
  • The paper white luminance is controlled using the SDR content brightness slider in the Settings app, while the peak white luminance is through the Auto HDR Intensity slider in the game bar.[6]

Auto HDR uses both an explicit whitelist (e.g. Valorant) as well as swap buffer information to determine if a game is eligible for Auto HDR. The main requirement for a game is the use of a DXGI flip model for presentation — this is also why Windows 11's windowed optimizations are a requirement for Auto HDR as this extends the support to thousands of older DirectX 10 and DirectX 11 games that would otherwise not be supported by the feature.

DirectX 11-12

For some DirectX 11-12 games, Auto HDR can be forcefully enabled using the third-party autohdr_force tool.

Most remaining unsupported DirectX 11-12 games often only requires the use of Special K and its flip model override (enabled by default) to make them eligible for Auto HDR.[7] Special K's flip model override are capable of handling a few edge cases which Windows 11's built-in windowed optimizations does not handle.

DirectX 9

For DirectX 9 games the use of dgVoodoo 2 to translate them to DirectX 11 often makes them eligible as well.[8]

OpenGL/Vulkan

Some drivers offer the option to present OpenGL and Vulkan games via a DXGI swapchain which will in many cases allow Auto HDR to kick in, though it might require the game to be configured to use a windowed or borderless windowed display mode.

  • AMD owners using driver version 23.7.1 or newer can enable HDR in Windows settings. This will enable the DXGI swapchain present on all OpenGL and Vulkan apps (minus a few excluded apps hardcoded in the driver). Alternatively, enabling OpenGL Triple Buffering in the driver control panel will also cause the driver to present using DXGI.
  • Nvidia owners using driver version 526.61 or newer can set Vulkan/OpenGL present method in the Nvidia Control Panel > Manage 3D Settings page to Prefer layered on DXGI Swapchain. Nvidia Profile Inspector can extend the support even further to games running through DXVK or emulators.[9]


References

  1. Verified by User:Aemony on 2018-04-09
    This is the state of the thing now, at least. I hope that Microsoft/Nvidia/someone comes up with an automatic SDR->HDR translation layer soon, because currently it's quite bad.
  2. 2.0 2.1 YouTube - Half-Life 2: Lost Coast Developer Commentary
  3. Verified by User:Aemony on 2022-05-22
    Microsoft does not mention D3D10 support, but I have confirmed this with both Just Cause 2 and Renegade Ops, two D3D10 exclusive titles, as well as S.T.A.L.K.E.R.: Clear Sky in D3D10 mode.
  4. YouTube - What's New with High Dynamic Range in DirectX Games - Auto HDR for PC - last accessed on 2022-05-05
  5. Microsoft Support - Calibrate your HDR display using the Windows HDR Calibration app - last accessed on 2023-02-14
  6. Verified by User:Aemony on 2023-03-20
    Reaffirmed this in 2023 using Helltaker in a borderless window and adjusting the SDR content brightness slider in real-time.
  7. Verified by User:Aemony on 2022-05-05
    This has long been known among the Special K HDR community, and it is why Microsoft is working on windowed optimizations for Windows 11 which will essentially do the same as Special K's flip model override feature and expand Auto HDR to thousands of more games as a result.
  8. Verified by User:Aemony on 2022-05-22
    A minor note is that while this enables the use of Auto HDR in games using older APIs, technically speaking HDR rendering was first introduced in DirectX 9, so such games will probably see the best results.
  9. Reddit - PSA - You can now elevate OpenGL/Vulkan games to a DXGI Swapchain on today's drivers (526.47) - last accessed on 2023-07-30