Backward Compatible Extended Dynamic Range Video Encoding
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Solution Overview
Problem
Conventional standard dynamic range (SDR) video systems cannot effectively utilize unused coding space to encode and display extended dynamic range (EDR) video, limiting the dynamic range and precision of displayed images.
Innovation Solution
The method involves encoding EDR video as N-bit video, using additional code values beyond the standard range to represent extended dynamic range and precision, while maintaining backward compatibility with SDR systems, by mapping input video values to EDR channel code values using inverse gamma encoding and log encoding for standard and high luminance values respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional SDR video encoding is used, then compatibility with existing infrastructure is maintained, but the dynamic range and precision of displayed images are limited
Solution Approach 1:
The patent embeds EDR video data within the existing SDR video coding framework by utilizing unused code values (0-15 and 240-255) in the 8-bit code space. This nesting approach allows EDR content to be contained within SDR containers, enabling both SDR and EDR systems to process the same bitstream without requiring separate infrastructure.
Solution Approach 2:
The patent extends the dynamic range by utilizing the previously unused upper and lower portions of the 8-bit code value spectrum. By mapping EDR luminance values to include code values 0-15 (below black level) and 240-255 (above white level), the system effectively adds new dimensions to the existing code space without increasing bit depth.
2Measurement precision
If additional code values are used to represent EDR, then dynamic range extension is achieved, but compatibility with legacy SDR systems may be compromised
Solution Approach 1:
The patent creates a universal video coding scheme where the same N-bit code values serve dual purposes: standard code values (16-239 for 8-bit) maintain SDR compatibility while additional code values (0-15, 240-255) enable EDR functionality. This multi-functionality allows a single encoding system to serve both legacy and advanced display systems.
Solution Approach 2:
The patent modifies the interpretation of code values based on the display system's capabilities. EDR systems interpret code values 0-255 as representing extended luminance ranges including below-black and above-white levels, while SDR systems automatically clip these extreme values to the standard 16-239 range, maintaining backward compatibility without requiring system-specific encoding variations.
3Measurement precision
If code values beyond standard range are utilized, then precision at extreme luminance levels is improved, but potential quality side effects may occur
Solution Approach 1:
The patent applies different encoding strategies to different luminance regions: standard gamma encoding is used for mid-range luminance values (16-239) to maintain compatibility, while logarithmic or linear encoding is applied to extreme luminance values (0-15 and 240-255) to maximize dynamic range representation. This local differentiation optimizes precision where needed while minimizing artifacts in each region.
Data Source
AI summary
In some embodiments, an encoding method for generating an extended dynamic range (EDR) channel in response to an input video channel, such that the EDR channel's code values consist of code values in a range from a standard black level, X, through a standard white level, Z, and an additional code value set. The EDR channel is displayable with standard dynamic range and standard precision by a standard dynamic range video system which maps to the level, X, any of the EDR channel's values less than X, and maps to the level, Z, any of the EDR channel's values greater than Z, and is displayable with an extended dynamic range greater than the standard dynamic range and/or a precision greater than the standard precision by an EDR video system. Other aspects are systems configured to perform embodiments of the encoding method, and methods and systems for displaying EDR video.