These built-in post-processing shaders are designed to perform tone-mapping of High Dynamic Range (HDR) images for presentation on traditional monitors, as well as the signal generation for HDR10 when outputting to 4k UHD wide gamut displays.

Related tutorial: Using HDR rendering

class DirectX::ToneMapPostProcess : public DirectX::IPostProcess

Header

Initialization

Construction requires a Direct3D 11 device.

std::unique_ptr<ToneMapPostProcess> toneMap;
toneMap = std::make_unique<ToneMapPostProcess>(device);

For exception safety, it is recommended you make use of the C++ RAII pattern and use a std::unique_ptr or std::shared_ptr

Shader selection

The shader selection is based on the combination of the tonemap operator and the electro-optical transfer function.

The tonemap operator is controlled by calling SetOperator:

• None: No tonemap operator is applied, and the input is passed through the shader to the render target unchanged.
• Saturate: A simple clamp to the range 0 to 1 is applied after multiplying by the exposure level.
• Reinhard: The classic Reinhard local tonemap operator is applied after multiplying by the exposure level.
• ACESFilmic: A tonemap operator consistent with the recommended curve for use by the Academy Color Encoding System.

The electro-optical transfer function is controlled by calling TransferFunction:

• Linear: A simple linear transfer function is applied.
• SRGB: The approximate sRGB display curve (Gamma 2.2) is applied.
• ST2084: A Rec.709 to Rec.2020 color primary rotation and ST.2084 display curve is applied for HDR10 output.

For Xbox One, there is also a SetMRTOutput boolean for selecting special shaders that generate both the HDR10 output for display as well as a tone-mapped GameDVR signal using Multiple Render Targets.

Properties

• SetHDRSourceTexture is used to set the linear texture Shader Resource View that provides the original High Dynamic Range (HDR) signal, which is typically in a floating-point format.

• SetExposure sets the exposure value for the tonemap operators. The default is 0.0 (which is a linear multiplier of 1.0)

• SetST2084Parameter sets the nits level for paper white when applying the ST.2084 display curve. Reference paper white is 80 nits for a cinema setup, but defaults to 200.0 which is good for typical CRT viewing conditions.

• SetColorRotation sets the colorspace transformation matrix used for HDR10 output. It defaults to rotating HDTV (Rec.709) color primaries into UHDTV (Rec.2020). There are two overloads of this function: One takes an enum with a few predefined matrices; the other takes a custom matrix.

Exceptions

Error reporting uses the standard C++ exceptions std::exception, std::invalid_argument, std::runtime_error, or std::bad_alloc.

Further reading

Reinhard et al., "Photographic tone reproduction for digital images", ACM Transactions on Graphics, Volume 21, Issue 3 (July 2002). ACM DL
Tone mapping
High-dynamic-range video