HDR Picture Encoding Using Default dQP Table and Offset
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Solution Overview
Problem
Current technologies lack a specific solution for encoding High Dynamic Range (HDR) content represented with the Hybrid-Log Gamma (HLG) transfer function, which requires handling different statistical distributions based on scene-referred or display-referred signals and peak luminance, leading to increased complexity and memory needs in encoding and decoding processes.
Innovation Solution
A method and device for encoding a picture block that determines a quantization parameter QP using a default dQP table and QP offset, reducing the number of codec parameters and tables needed, thereby simplifying the encoding process and improving coding efficiency for both HLG and Perceptual Quantizer (PQ) signal representations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple sets of codec parameters are used to handle different HLG signal cases (scene-referred vs display-referred, different peak luminances), then the coding efficiency is improved, but the device complexity and memory requirements increase significantly
Solution Approach 1:
The patent creates a universal codec parameter set that works for both scene-referred and display-referred HLG signals across different peak luminances. By using a single default dQP table and QP offset mechanism, the system achieves multi-functionality without requiring separate parameter sets for each signal type, thus resolving the contradiction between coding efficiency and device complexity
Solution Approach 2:
The patent modifies the QP determination process by introducing a default dQP table and QP offset parameters that can be applied universally. This parameter change allows the same base table to adapt to different HLG signal characteristics through offset adjustments, maintaining coding efficiency while reducing the need for multiple complete parameter sets
2Measurement precision
If separate codec parameter sets are implemented for different HLG and PQ signal representations, then the measurement precision for optimal encoding is improved, but the quantity of substance (memory needs) increases
Solution Approach 1:
The patent extracts the essential differences between different HLG and PQ signal representations into separate manageable components: a default dQP table for base quantization and QP offset values for signal-specific adjustments. This extraction allows precise handling of different signal types while storing only the necessary deviation data, significantly reducing memory requirements compared to storing complete separate parameter sets
Solution Approach 2:
The patent segments the codec parameters into two functional parts: a shared default dQP table that contains the base quantization parameters, and signal-specific QP offset values. This segmentation allows the system to maintain precise encoding for different signal types while minimizing the total amount of stored data, as the offsets are much smaller than complete parameter sets
Data Source
AI summary
A method for decoding a block of a picture represented in a current HDR/WCG format is disclosed. The method comprises receiving a bitstream representative of a coded block of picture, an indication representative of a default d QP table (index_d QP_table), an indication representative of a QP offset (slice_qp_delta); determining a quantization parameter responsive to the current format based on the default d QP table and the QP offset; decoding the coded block of a picture using the determined QP. Corresponding encoding method, transmitting method, decoding device, encoding device and transmitting device are disclosed. Besides an embodiment relative to adapting generic codec parameters to any HDR/WCG format as done for d QP table is also disclosed.