HDR to EDR Tone Mapping for Brightness Detail Preservation
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Solution Overview
Problem
HDR video playback on EDR display devices does not efficiently utilize the increased brightness range, leading to loss of details in moderately bright and very bright values when HDR video is played on SDR or EDR devices with limited peak brightness.
Innovation Solution
A video playback system that includes decision logic to determine the peak brightness of the target display device and select an HDR-to-EDR tone mapping mode, using a tone mapper to apply a tone mapping function based on the display device's peak brightness, ambient light, and video content, effectively expanding or compressing brightness ranges to optimize rendering on EDR devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If HDR video is played back on an SDR display device, then the video can be displayed on widely compatible devices, but details in moderately bright and very bright values are lost due to brightness clipping
Solution Approach 1:
The patent applies parameter changes by transforming the brightness parameter through tone mapping functions. The HDR video with wide brightness range (0-10000 nits) is converted to EDR video with intermediate brightness range (0-400/600 nits) using adaptive tone mapping that preserves brightness details while adapting to display device capabilities
Solution Approach 2:
The patent introduces EDR video as an intermediary format between HDR and SDR. The tone mapping process creates EDR video with extended brightness headroom (400-600 nits) that serves as a intermediate representation, preserving more brightness information than direct SDR conversion while being displayable on EDR devices
2Illumination intensity
If HDR video is played back on an EDR display device without efficient tone mapping, then the device's enhanced brightness range is not utilized, but implementing tone mapping increases processing complexity
Solution Approach 1:
The patent implements dynamic tone mapping where the tone mapping function adapts based on scene characteristics, ambient light conditions, and target display device properties. The decision logic dynamically selects between different tone mapping modes (HDR-to-EDR, HDR-to-SDR, or direct HDR playback) to optimize brightness utilization while managing processing complexity
Solution Approach 2:
The patent segments the tone mapping process into distinct functional components: decision logic for mode selection, tone mapping function application, and adaptive parameter adjustment. This segmentation allows the system to apply complex tone mapping only when necessary while maintaining simpler processing paths for compatible scenarios
3Ease of operation
If brightness values above a certain threshold are compressed to a small range on an SDR display device, then the video can be displayed, but the wide range of bright values in HDR video is represented with limited detail
Solution Approach 1:
The patent changes the brightness parameter representation by applying tone mapping functions that non-linearly transform HDR brightness values to EDR brightness values. This transformation preserves the relative relationships and details of bright values while adapting them to the EDR display device's capabilities, maintaining both playback feasibility and brightness precision
Data Source
AI summary
Innovations in rendering of high dynamic range (“HDR”) video on a display device having enhanced dynamic range (“EDR”). The peak brightness for an EDR display device is lower than the peak brightness for a typical HDR display device but higher than the peak brightness for a typical display device having standard dynamic range. The increased range of brightness values in an EDR display device can be utilized effectively to show bright highlights of the HDR video. For example, decision logic is configured to evaluate a peak brightness of a target display device and select an HDR-to-EDR tone mapping mode. A tone mapper is configured to apply tone mapping to input values for the sample values of HDR video, according to a tone mapping function, thereby producing output values for sample values of EDR video.