HDMI Display Metadata Transmission for HDR Rendering
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Solution Overview
Problem
Current display systems face challenges in rendering high dynamic range (HDR) images due to limitations in dynamic range, color gamut, and resolution, leading to noticeable errors and degradations in rendered images compared to the original scene-referred images.
Innovation Solution
The transmission of display management metadata over a video link allows for the delivery of scene-referred HDR content with reference code values and mapping metadata, enabling rendering devices to map these values to optimal pixel values that exploit their maximum capabilities, regardless of the device's dynamic range, color gamut, or resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If scene-referred HDR images with large dynamic range are transmitted to displays with limited dynamic range, then the original scene-referred dynamic range is preserved in transmission, but visually noticeable errors and degradations occur in rendered images
Solution Approach 1:
The patent applies preliminary action by pre-calculating and embedding transfer characteristics (mapping functions) into the HDR image data during encoding. This allows the display device to perform accurate tone mapping without real-time computation, ensuring that the limited dynamic range of the display is optimally utilized while maintaining fidelity to the original scene-referred image. The transfer characteristics are prepared in advance to guide the mapping process from HDR to SDR space.
Solution Approach 2:
The patent employs parameter changes by transforming the dynamic range parameters of the image data. It converts scene-referred HDR values with large dynamic range into display-referred SDR values with limited dynamic range, using embedded transfer characteristics to control the transformation. This parameter transformation allows the image to adapt to different display capabilities while preserving perceptual quality.
2Adaptability or versatility
If device-specific image transformations are applied to adapt content to display capabilities, then the content can be rendered on various devices, but large amounts of visually noticeable errors and degradations occur
Solution Approach 1:
The patent implements universality by creating a universal solution that works across different display devices. It embeds transfer characteristics directly in the HDR image data, making the content self-descriptive and adaptable to any display device without requiring device-specific processing or multiple versions of the same content. This universal approach ensures consistent quality across diverse display capabilities.
Solution Approach 2:
The patent uses transfer characteristics as an intermediary between the source HDR content and the target SDR display. These embedded transfer characteristics act as a mediator that guides the transformation process, ensuring that the adaptation from HDR to SDR maintains perceptual fidelity. The intermediary contains the necessary mapping information to bridge the gap between different dynamic ranges without introducing visible errors.
3Adaptability or versatility
If standard dynamic range (SDR) displays are used to render high dynamic range (HDR) content, then compatibility with existing displays is maintained, but the full dynamic range and perceptual qualities of the original image cannot be exploited
Solution Approach 1:
The patent applies preliminary action by pre-computing optimal transfer characteristics that maximize the utilization of the SDR display's limited dynamic range. Instead of losing information, the embedding of these characteristics allows the SDR display to render the HDR content as faithfully as possible within its constraints, preserving perceptual qualities through carefully designed mapping functions that are prepared in advance.
Data Source
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AI summary
In an embodiment, a source video signal comprising reference code values and mapping function parameters for one or more mapping functions to map the reference code values to device-specific pixel values. The reference code values and the mapping function parameters are combined into first video frames in a first video signal format. The mapping function parameters represent DM metadata carried in the first video frames. Second video frames in a second video signal format are generated based on the first video frames in the first video signal format and a mapping between the first video signal format and the second video signal format. The second video frames are sent to a video sink device through the video link in an encoded video signal of the second video signal format.