10E Dynamic Metadata for Color Transforms of HDR and WCG Images
- Project Type:
- SMPTE Engineering Project (ANSI)
- Project Contact:
- Lars Borg
- Project State:
- Progress Report:
- Parts 0: OV: Published Jan 25, 2017 1: ST: published July 15, 2016 2: ST: Published Jan 25, 2017 10: ST: published July 15, 2016 20: ST: published Aug 1, 2016 30: ST: published Aug 1, 2016 40: ST: published Sep 14, 2016
Start: 2014-12-11 Completed: 2017-01-25
- Project Description:
- Develop a standard for the semantics and representation of metadata specifying content-dependent color volume transformation parameters to smaller color volumes in mastering applications.
- Problem to be solved:
High Dynamic Range / Wider Color Gamut content captured for example using the newly standardized SMPTE ST 2084:2014 Electro-Optical Transfer Function requires a set of industry standardized metadata to ensure a consistent transformation of this content to the existing BT.709 (add in SMPTE references) standard. This metadata is bounded by the characteristics of the mastering display as defined in SMPTE ST 2086:201x, but to ensure creative intent is maintained, content dependent metadata is also required. This standard will define the required metadata set. If color mapping is performed without this metadata, the resulting out of gamut content will suffer severely in visual quality due to clipping.
The SMPTE UHDTV Ecosystem Study Group has reported on this subject in Annex B “High Dynamic Range Imaging” and Annex C “Standard Dynamic Range Color Space Conversion” in the report dated March 28, 2014. The example cited above aligns closely with section C.4 and C.5 specifically cautioning the conversion between UHDTV and HDTV/SDTV.
The science of color volume mapping has seen major advances recently. A one-size-fits-all solution to map between different color volumes does not currently exist. The logical extension to the current color volume mapping techniques common in image processing is the use of a content-dependent dynamically parameterized color transformation. The color volume mapping transformation is derived for every scene/segment based on the metadata that characterizes the content. For example, a very dark scene will be mapped differently from a very bright scene when transforming from a large color volume to a more restricted color volume. This can be effectively achieved only when this transformation is guided by metadata.
- Project scope:
Develop multi-part standards for specifying the semantics and representation of content-dependent metadata needed for color volume transformation of high dynamic range and wide color gamut imagery to smaller color volumes (e.g. BT.709 or Digital Cinema) in mastering applications. The metadata entries constitute the logical concept (semantics) for immediate work followed by the physical encoding (representation) specification based on an extensible metadata international standard such as ISO 16684. The standards should specify metadata necessary to support the mastering of high dynamic range and wide color gamut content for next generation distribution as well as physical media formats.
The metadata should allow for parameterized color transformation that is variable along a timeline. The resulting metadata standard should include clip-based with optional title-level, shot-level, frame-level, and other applicable groupings of color volume transformation metadata and may include both public and private metadata.
The metadata is carried in parallel and synchronized with the mastered content and can be used for real time transformation during mastering or for a deferred transformation in distribution.
The metadata should also characterize certain colorimetric attributes of the content to aid in the transformation process. One example would be minimum, average, maximum luminance values as well as parametric controls for the color volume transformation process derived during mastering performed in a perceptually linear color space.
The standards implementation should not be tied to any specific hardware.
The metadata set specified by the resulting standard should use the mastering display color volume metadata specified in ST 2086 “Mastering Display Color Volume Metadata Supporting High Luminance and Wide Color Gamut Images”.
Specific methods for generation and use of the metadata are out of the scope of this standard.
- Specific tasks:
Develop multi-part standards (a vendor-agnostic framework and baseline, with extensions for new data types) for specifying the semantics and representation of content-dependent metadata needed for color volume transformation of high dynamic range and wide color gamut imagery to smaller color volumes (e.g. BT.709 or Digital Cinema) in mastering applications.
Define a metadata representation suitable for carriage of the defined metadata for offline content production following ISO 16684-1:2012, “Graphic technology – Extensible metadata platform (XMP) specification – Part 1: Data model, serialization and core properties” specifications.
- Form of output:
- Patent Declaration Received? (To be completed prior to FCD)
- Patent declarations:
(patent statement revised to apply to 2094-10)