ToneMapPostProcess

DirectXTK	PostProcess

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

Header

#include "PostProcess.h"

Initialization

Construction requires a Direct3D 12 device, shader selection parameters, and state description:

std::unique_ptr<ToneMapPostProcess> postProcess;

RenderTargetState rtState(m_deviceResources->GetBackBufferFormat(),
    m_deviceResources->GetDepthBufferFormat());

postProcess = std::make_unique<ToneMapPostProcess>(device, rtState,
    ToneMapPostProcess::ACESFilmic,
    ToneMapPostProcess::SRGB);

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 when creating the instance.

The tonemap operator can be:

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 can be:

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 mrt 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 Descriptor 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.

enum	Notes
`HDTV_to_UHDTV`	Rec.709 to Rec.2020
`DCI_P3_D65_to_UHDTV`	DCI-P3-D65 (a.k.a Display P3 or P3D65) to Rec.2020
`HDTV_to_DCI_P3_D65`	Rec.709 to DCI-P3-D65 (a.k.a Display P3 or P3D65)