Intra LM Prediction Reference Pixel Reduction

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Solution Overview

Problem

Current video compression techniques face challenges in achieving high compression ratios and reducing implementation complexity without compromising video quality, especially in scenarios with limited network resources.

Innovation Solution

A video codec that generates a prediction block for chroma blocks by downsampling neighboring luma and chroma samples, using either every Nth sample or sliding averages, to reduce the number of samples used in intra prediction calculations, thereby simplifying the LM mode and maintaining coding performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If all neighboring luma and chroma samples are used in intra prediction calculations, then prediction accuracy is improved, but computational complexity increases

Engineering Contradiction:
Improveprediction accuracyVSAvoidcomputational complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts only the most relevant neighboring samples for prediction calculations. Specifically, it selects samples based on gradient direction (using top neighbors for vertical gradients and left neighbors for horizontal gradients) rather than using all available neighbors, thereby reducing computational complexity while maintaining prediction accuracy.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies different sampling strategies to different regions based on local characteristics. It uses gradient calculation to determine the dominant direction (vertical or horizontal) and selectively uses neighbors from that direction, making the prediction process adaptive to local image structure rather than uniformly processing all neighbors.

Inventive Principle:
Principle #3Local quality

2Measurement precision

If more neighboring samples are processed, then prediction precision is improved, but processing time increases

Engineering Contradiction:
Improveprediction precisionVSAvoidprocessing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent extracts only the necessary subset of neighboring samples based on gradient direction. By calculating the gradient and selecting samples only from the dominant direction (top or left), it avoids processing all neighboring samples, thereby reducing processing time while maintaining prediction precision.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies partial action by using only the required number of samples from the dominant direction rather than processing all available samples. This selective approach reduces the amount of computation needed while still achieving accurate predictions.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP2805496B1Reference pixel reduction for intra LM prediction
Publication Date: 2016.12.21 HUAWEI TECH CO LTD
  • EP2805496B1 patent drawingFigure 1
  • EP2805496B1 patent drawingFigure 2
  • EP2805496B1 patent drawingFigure 3

AI summary

A video codec comprising a processor configured to generate a prediction block for a chroma block, wherein the prediction block comprises a predicted chroma sample, wherein the predicted chroma sample is based on a filtered reconstructed luma sample located in a corresponding reconstructed luma block, a plurality of downsampled filtered reconstructed luma samples located in positions neighboring the corresponding reconstructed luma block, and a plurality of downsampled chroma samples located in positions neighboring the chroma block.