High Dynamic Range (HDR), often in combination with wide color gamut (WCG), is a way to improve the colors shown on screens. VizEngine 3.11 offers experimental support for HDR.

Supported color formats

These are the supported SDR/HDR color formats of Viz Engine 3.11 (or higher):

SDR	HDR
ITU-R BT.601	ITU-R_BT.2100 PQ
ITU-R BT.709	ITU-R_BT.2100 HLG
ITU-R_BT.2020	ITU-R_BT.2100 SLOG3

Those standards are mainly known as HDR10.

BT 2020

BT.2020 is a color space with a WCG. It covers a larger subset of visible colors than, for example, BT.709. Currently, all HDR settings in VizEngine use the BT.2020 color space with ten bits per component (bpc) color depth.

PQ (Perceptual Quantization)

PQ is standardized as SMPTE ST 2084. PQ defines the luminance levels up to 10,000 cd/m2 (nit).

HLG (Hybrid Log-Gamma)

HLG provides a relative value tied to the gamma and logarithmic curve. This system supports practical luminance levels from 1,000 up to 2,000 cd/m2. HLG is compatible with conventional SDR systems, so TVs that do not support HDR can reproduce HDR.

SLOG3

Requirements

Matrox System Topology video card (X.mio3 or DSX LE4).
1080p or UHD resolution.

Limitations

HDR input is only supported via DVE; consequently, HDR input is not possible on a DSX LE4.
UHD HDR input at 59.94 FPS exceeds the processing capabilities of an X.mio3.
Currently, no conversions between HDR and SDR, or between different HDR standards, are supported.

Configuration

Most of the settings required for HDR are not yet accessible through the GUI. Those have to be changed in the VizEngine config file.

Output

Set the output format to 1080p or UHD.
Change the output colorimetry: output_colorimetry = ITUR_BT_2100_HLG

Other options are ITUR_BT_2020, ITUR_BT_2100_PQ, and ITUR_BT_2100_SLOG3.
Specifying ITUR_BT_601 or ITUR_BT_709 is possible, but redundant. BT.601 is always used for SD resolutions (NTSC, PAL) and BT.709 is the default value for all other resolutions.

Input

Currently, only live and clip input are supported on X.mio3 video cards.

Set the input to the same resolution and framerate as the output.
Set the colorimetry (live_colorimetryX or clip_colorimetryX, respectively) to the same colorimetry as the output.
Use the input as DVE.

Currently, no conversions between different frame rates, resolution or colorimetries are supported when HDR is used. Clip input channels can only play clips that have the same resolution.

Renderer output

Set the renderer to use 16 bpc: bits_per_channel = 16
Set the color space conversion (CSC) to shader: rgb_2_yuv = 1

Note: When HDR is enabled, shader CSC and GPU direct can be used in combination.