Luma Mapping Chroma Scaling for Video Intra Prediction
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Solution Overview
Problem
Current video encoding and decoding methods face challenges in enhancing intra prediction performance when restored samples around the current block are not available, particularly due to the increasing volume and complexity of video data, which requires more efficient compression techniques to manage data effectively.
Innovation Solution
The method employs a luma mapping function to derive luma reference samples for intra prediction, converting luma signals between an original and a mapping area, and signaling parameters for luma mapping chroma scaling (LMCS) to manage parameter sets based on form and identifier, enabling effective intra prediction even without neighboring restoration samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional intra prediction methods are used without luma mapping, then the encoding process is simpler, but intra prediction performance deteriorates when restored samples are not available
Solution Approach 1:
The patent applies parameter changes by transforming luma signals through a mapping function that converts original luma values to mapped luma values using piecewise linear transformation with configurable parameters (breakpoints, slopes, intercepts). This allows the system to adapt prediction performance to different content characteristics while maintaining a standardized encoding framework, resolving the contradiction between reliability and complexity.
Solution Approach 2:
The patent introduces an intermediary mapping domain between the original luma signal and the prediction process. Instead of directly using restored samples or original signals, the system transforms luma values through a mapping function that acts as a mediator, enabling more accurate prediction when restored samples are unavailable while keeping the overall system structure manageable.
2Productivity
If video data is compressed using existing techniques, then data volume is reduced, but coding efficiency and image quality continue to deteriorate as video resolution and frame rate increase
Solution Approach 1:
The patent changes the parameter space by applying luma mapping transformation that redistributes quantization errors according to human visual perception characteristics. By transforming luma values through configurable mapping functions with adjustable parameters, the system achieves better coding efficiency at high resolutions while minimizing perceived quality loss, directly addressing the contradiction between productivity and information loss.
Solution Approach 2:
The patent applies local quality by using piecewise linear mapping functions with different breakpoints, slopes, and intercepts for different luma value ranges. This allows the system to apply different transformation characteristics to different parts of the luma signal spectrum, optimizing coding efficiency for specific content types and regions while maintaining overall image quality, thus resolving the contradiction between productivity and information loss.
3Measurement precision
If luma mapping function is applied for intra prediction, then prediction performance is enhanced by reflecting perceptual characteristics, but encoding and decoding complexity increases
Solution Approach 1:
The patent uses parameter changes to define mapping functions with configurable breakpoints, slopes, and intercepts that can be optimized for different prediction scenarios. By adjusting these parameters, the system achieves higher prediction accuracy that reflects human perceptual characteristics while controlling processing complexity through a standardized parameter-based framework rather than complex algorithms.
Solution Approach 2:
The patent applies preliminary action by pre-defining mapping functions and their parameters that can be selected and applied during encoding/decoding. The mapping relationships are established in advance through parameter configuration, allowing the system to achieve high prediction accuracy without requiring complex real-time computations, thus resolving the contradiction between measurement precision and device complexity.
Data Source
AI summary
The present disclosure intends to provide a video encoding/decoding method of performing intra prediction for a current block by using luma reference samples derived based on a luma mapping function in order to enhance performance of intra prediction for a case where restored samples around the current block to be predicted cannot be used.