VkColorSpaceKHR

Possible values of VkSurfaceFormatKHR::colorSpace, specifying the color spaces that a presentation engine can accept, are:

typedef enum VkColorSpaceKHR {
    VK_COLOR_SPACE_SRGB_NONLINEAR_KHR = 0,
    VK_COLORSPACE_SRGB_NONLINEAR_KHR = VK_COLOR_SPACE_SRGB_NONLINEAR_KHR,
} VkColorSpaceKHR;

VK_COLOR_SPACE_SRGB_NONLINEAR_KHR specifies support for the images in sRGB color space, encoded according to the sRGB specification.
VK_COLOR_SPACE_DISPLAY_P3_NONLINEAR_EXT specifies support for the images in Display-P3 color space, encoded using a Display-P3 transfer function.
VK_COLOR_SPACE_EXTENDED_SRGB_LINEAR_EXT specifies support for the images in extended sRGB color space, encoded using a linear transfer function.
VK_COLOR_SPACE_EXTENDED_SRGB_NONLINEAR_EXT specifies support for the images in extended sRGB color space, encoded according to the scRGB specification.
VK_COLOR_SPACE_DISPLAY_P3_LINEAR_EXT specifies support for the images in Display-P3 color space, encoded using a linear transfer function.
VK_COLOR_SPACE_DCI_P3_NONLINEAR_EXT specifies support for the images in DCI-P3 color space, encoded according to the DCI-P3 specification. Note that values in such an image are interpreted as XYZ encoded color data by the presentation engine.
VK_COLOR_SPACE_BT709_LINEAR_EXT specifies support for the images in BT709 color space, encoded using a linear transfer function.
VK_COLOR_SPACE_BT709_NONLINEAR_EXT specifies support for the images in BT709 color space, encoded according to the BT709 specification.
VK_COLOR_SPACE_BT2020_LINEAR_EXT specifies support for the images in BT2020 color space, encoded using a linear transfer function.
VK_COLOR_SPACE_HDR10_ST2084_EXT specifies support for the images in HDR10 (BT2020) color space, encoded according to SMPTE ST2084 Perceptual Quantizer (PQ) specification.
VK_COLOR_SPACE_HDR10_HLG_EXT specifies support for the images in HDR10 (BT2020) color space, encoded according to the Hybrid Log Gamma (HLG) specification.
VK_COLOR_SPACE_ADOBERGB_LINEAR_EXT specifies support for images in Adobe RGB color space, encoded using a linear transfer function.
VK_COLOR_SPACE_ADOBERGB_NONLINEAR_EXT specifies support for the images in Adobe RGB color space, encoded according to the Adobe RGB specification (approximately Gamma 2.2).
VK_COLOR_SPACE_PASS_THROUGH_EXT specifies that color components are used as is. This is intended to allow applications to supply data for color spaces not described here.
VK_COLOR_SPACE_DISPLAY_NATIVE_AMD specifies support for the display’s native color space. This matches the color space expectations of AMD’s FreeSync2 standard, for displays supporting it.

In the initial release of the VK_KHR_surface and VK_KHR_swapchain extensions, the token VK_COLORSPACE_SRGB_NONLINEAR_KHR was used. Starting in the 2016-05-13 updates to the extension branches, matching release 1.0.13 of the core API specification, VK_COLOR_SPACE_SRGB_NONLINEAR_KHR is used instead for consistency with Vulkan naming rules. The older enum is still available for backwards compatibility.

In older versions of this extension VK_COLOR_SPACE_DISPLAY_P3_LINEAR_EXT was misnamed VK_COLOR_SPACE_DCI_P3_LINEAR_EXT. This has been updated to indicate that it uses RGB color encoding, not XYZ. The old name is deprecated but is maintained for backwards compatibility.

In older versions of the VK_EXT_swapchain_colorspace extension, VK_COLOR_SPACE_DOLBYVISION_EXT was exposed. The intent was to indicate the presentation engine shall decode an image using the SMPTE ST 2084 Perceptual Quantizer (PQ) EOTF, and then apply a proprietary OOTF to process the image. However, Dolby Vision profile 8.4 describes an encoding using the Hybrid Log Gamma (HLG) OETF, and there is no swapchain extension for signaling Dolby Vision metadata to be used by a proprietary OOTF. This enum is deprecated but is maintained for backwards compatibility.

For a traditional Linear or non-gamma transfer function color space use VK_COLOR_SPACE_PASS_THROUGH_EXT.

The presentation engine interprets the pixel values of the R, G, and B components as having been encoded using an appropriate transfer function. Applications should ensure that the appropriate transfer function has been applied. Textures Output Format Conversion requires that all implementations implicitly apply the sRGB EOTF^-1 on R, G, and B components when shaders write to an sRGB pixel format image, which is useful for sRGB color spaces. For sRGB color spaces with other pixel formats, or other non-linear color spaces, applications can apply the transfer function explicitly in a shader. The A channel is always interpreted as linearly encoded.

This extension defines enums for VkColorSpaceKHR that correspond to the following color spaces:

Table 1. Color Spaces and Attributes
Name	Red Primary	Green Primary	Blue Primary	White-point	Transfer function
DCI-P3	1.000, 0.000	0.000, 1.000	0.000, 0.000	0.3333, 0.3333	DCI P3
Display-P3	0.680, 0.320	0.265, 0.690	0.150, 0.060	0.3127, 0.3290 (D65)	Display-P3
BT709	0.640, 0.330	0.300, 0.600	0.150, 0.060	0.3127, 0.3290 (D65)	BT709
sRGB	0.640, 0.330	0.300, 0.600	0.150, 0.060	0.3127, 0.3290 (D65)	sRGB
extended sRGB	0.640, 0.330	0.300, 0.600	0.150, 0.060	0.3127, 0.3290 (D65)	scRGB
HDR10_ST2084	0.708, 0.292	0.170, 0.797	0.131, 0.046	0.3127, 0.3290 (D65)	ST2084 PQ
HDR10_HLG	0.708, 0.292	0.170, 0.797	0.131, 0.046	0.3127, 0.3290 (D65)	HLG
Adobe RGB	0.640, 0.330	0.210, 0.710	0.150, 0.060	0.3127, 0.3290 (D65)	Adobe RGB

The transfer functions are described in the Transfer Functions chapter of the Khronos Data Format Specification.

Except Display-P3 OETF, which is:

\begin{aligned} E & = \begin{cases} 1.055 \times L^{1 \over 2.4} - 0.055 & \text{for}\ 0.0030186 \leq L \leq 1 \\\ 12.92 \times L & \text{for}\ 0 \leq L < 0.0030186 \end{cases} \end{aligned}

where L is the linear value of a color component and E is the encoded value (as stored in the image in memory).

For most uses, the sRGB OETF is equivalent.