Adaptive Transfer Function for HDR Video Encoding
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Solution Overview
Problem
Existing video encoding and decoding systems rely on fixed transfer functions, which are inadequate for handling the high dynamic range of HDR imaging, leading to inefficiencies in bit representation and processing within codecs.
Innovation Solution
Implementing an adaptive transfer function that dynamically determines a focus dynamic range for each scene or frame based on image characteristics, allowing for bit depth adjustment and efficient representation of HDR content within codecs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed transfer function is used for video encoding, then the encoding process is simple, but the system cannot efficiently handle high dynamic range content
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed transfer function to an adaptive transfer function that changes based on the content being processed. The system dynamically selects between different transfer functions (e.g., PQ transfer function for HDR content, gamma transfer function for SDR content) based on characteristics of the video data, allowing the encoding system to adapt to varying dynamic ranges without requiring complete redesign of the encoding architecture.
Solution Approach 2:
The patent implements parameter changes by varying the transfer function parameters according to content characteristics. The system determines whether to use a PQ transfer function with specific parameters or a gamma transfer function with different parameters, depending on the detected dynamic range of the content. This allows efficient HDR handling while maintaining backward compatibility with existing SDR workflows.
2Manufacturing precision
If more bits are used for internal processing to maintain HDR representation, then dynamic range is preserved, but processing efficiency decreases
Solution Approach 1:
The system changes the parameter representation approach by selecting appropriate transfer functions that match the content characteristics. For HDR content, the PQ transfer function provides efficient compression of high dynamic range values, while for SDR content, the gamma transfer function maintains standard processing efficiency. This parameter adaptation allows the system to achieve high dynamic range representation without consistently requiring increased bit depth for all processing operations.
Data Source
AI summary
A video encoding and decoding system that implements an adaptive transfer function method internally within the codec for signal representation. A focus dynamic range representing an effective dynamic range of the human visual system may be dynamically determined for each scene, sequence, frame, or region of input video. The video data may be cropped and quantized into the bit depth of the codec according to a transfer function for encoding within the codec. The transfer function may be the same as the transfer function of the input video data or may be a transfer function internal to the codec. The encoded video data may be decoded and expanded into the dynamic range of display(s). The adaptive transfer function method enables the codec to use fewer bits for the internal representation of the signal while still representing the entire dynamic range of the signal in output.