VK_EXT_hdr_metadata

Other Extension Metadata

Last Modified Date

2024-03-26

IP Status

No known IP claims.

Contributors

• Courtney Goeltzenleuchter, Google
• Sebastian Wick, Red Hat Inc.
• Tobias Hector, AMD

Description

This extension defines two new structures and a function to assign SMPTE (the Society of Motion Picture and Television Engineers) 2086 metadata and CTA (Consumer Technology Association) 861.3 metadata to a swapchain.

SMPTE 2086 metadata defines the color volume of the display on which the content was optimized for viewing and includes the color primaries, white point, and luminance range. When such content is reproduced on another display, this metadata can be used by the presentation engine to improve processing of images. For instance, values in the image can first be clamped to the color volume described in the metadata, and then what remains can be remapped to the color volume of the presentation engine.

CTA 861.3 metadata additionally includes the maximum intended luminance for the content and the maximum average light level across frames.

This extension does not define exactly how this metadata is used, however, it simply provides a mechanism to provide it to the presentation engine. Presentation engines may process the image based on the metadata before displaying it, resulting in the image being modified outside of Vulkan. For example, the clamping of colors in the image to the color volume may change those values in the image itself.

The metadata does not override or otherwise influence the color space and color encoding.

New Commands

• vkSetHdrMetadataEXT

New Structures

• VkHdrMetadataEXT
• VkXYColorEXT

New Enum Constants

• VK_EXT_HDR_METADATA_EXTENSION_NAME
• VK_EXT_HDR_METADATA_SPEC_VERSION
• Extending VkStructureType:
  • VK_STRUCTURE_TYPE_HDR_METADATA_EXT

Issues

1) Do we need a query function for the currently specified metadata?

No, Vulkan does not provide queries for state that the application can track on its own.

2) Should we specify default metadata if not specified by the application?

No, the metadata is optional and the absence of the metadata is well-defined.

Version History

• Revision 1, 2016-12-27 (Courtney Goeltzenleuchter)
  • Initial version
• Revision 2, 2018-12-19 (Courtney Goeltzenleuchter)
  • Correct implicit validity for VkHdrMetadataEXT structure
• Revision 3, 2024-03-26 (Tobias Hector & Sebastian Wick)
  • Clarifications and removal of erroneous "reference monitor" term