Video Decoder Tone-Curve Metadata for HDR and SDR Mapping
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Solution Overview
Problem
Existing technologies struggle to effectively manage the display of high-dynamic range (HDR) images on both HDR and standard dynamic range (SDR) displays, leading to suboptimal viewing experiences and compatibility issues.
Innovation Solution
A method for generating metadata that optimizes the trim-pass function parameters to minimize the difference between the decoder tone mapping curve and the target tone mapping curve, using techniques such as damped-least squares methods, to ensure accurate and aesthetically pleasing display of HDR images on various displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fixed tone mapping curve is used in the decoder, then the decoding process is simple and fast, but the display quality on different displays (HDR and SDR) is suboptimal
Solution Approach 1:
The encoder pre-calculates and stores multiple tone mapping curves corresponding to different display types (HDR and SDR displays with various luminance ranges) and transmits them as metadata to the decoder. This preliminary preparation allows the decoder to simply select the appropriate pre-computed curve based on display characteristics, achieving high display quality without complex real-time calculations.
Solution Approach 2:
The system changes the parameters of the tone mapping function by providing multiple pre-computed curves with different functional forms and parameters optimized for specific display types. The decoder selects the curve with parameters matched to the target display's luminance range and characteristics, thereby optimizing display quality without adding computational complexity to the decoding process.
2Manufacturing precision
If different tone mapping curves are provided for different display types, then display quality on both HDR and SDR displays is improved, but the metadata size and transmission bandwidth increase
Solution Approach 1:
Instead of transmitting complete tone mapping curves for each display type, the system transmits only the essential parameters (such as curve type identifier, luminance range, and key control points) that define each curve. The decoder then reconstructs or selects the appropriate curve based on these compact parameter sets, significantly reducing metadata size while maintaining the ability to optimize display quality for different display types.
3Manufacturing precision
If the tone mapping curve is optimized for HDR displays, then HDR display quality is superior, but compatibility with SDR displays deteriorates
Solution Approach 1:
The system creates a universal metadata structure that contains multiple tone mapping curves optimized for different display types (both HDR and SDR). The decoder determines the target display type and selects the appropriate curve from the provided set, ensuring that the same encoded video content can be optimally displayed on both HDR and SDR displays without sacrificing quality on either platform.
Data Source
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AI summary
A method for generating metadata for use by a video decoder for displaying video content encoded by a video encoder includes: (1) accessing a target tone mapping curve; (2) accessing a decoder tone curve corresponding to a tone curve used by the video decoder for tone mapping the video content; (3) generating a plurality of parameters of a trim-pass function used by the video decoder to apply after applying the decoder tone curve to the video content, wherein the parameters of the trim-pass function are generated to approximate the target tone curve with the combination of the trim-pass function and the decoder tone curve, and (4) generating the metadata for use by the video decoder, including said plurality of parameters of the trim-pass function.