Intra Prediction Reference Range for Lower-Bitrate Image Coding

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Solution Overview

Problem

The increasing demand for high-resolution and high-quality images leads to a surge in transmission and storage costs due to the increase in bit rate, necessitating a high-efficiency image compression technology.

Innovation Solution

An image encoding/decoding method that restricts intra prediction to use only a predetermined range of reference samples within a current block, enhancing compression efficiency through intra prediction and reference sample restriction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If high-resolution and high-quality images are transmitted, then image quality is improved, but transmission cost and storage cost increase

Engineering Contradiction:
Improveimage qualityVSAvoidtransmission cost and storage cost
Core Design Contradiction:
Manufacturing precisionVSLoss of energy

Solution Approach 1:

The patent extracts and transmits only the essential image information by using intra prediction to generate prediction blocks from reference samples, then encoding only the residual differences. This extraction of core information (residuals) rather than full image data reduces transmission and storage requirements while maintaining image quality.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the representation parameters of image data by transforming image blocks into prediction modes and residual values. By using intra prediction modes (e.g., planar, DC, angular modes) to represent image content and encoding only the deviations from these modes, the data is compressed efficiently while preserving quality.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If all available reference samples are used for intra prediction, then prediction accuracy is improved, but bit rate increases

Engineering Contradiction:
Improveprediction accuracyVSAvoidbit rate
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The patent extracts only the necessary reference samples within a predetermined range for intra prediction, rather than using all available reference samples. This selective extraction of relevant reference data maintains prediction accuracy for the current block while reducing the bit rate required to encode the prediction information.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies local quality by using different prediction strategies for different regions. By restricting intra prediction to reference samples within a predetermined range, the method optimizes prediction accuracy locally for each block while controlling overall bit rate, rather than uniformly using all reference samples across the entire image.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP4651480A1Image encoding/decoding method based on intra prediction, method for transmitting bitstream, and recording medium storing bitstream
Publication Date: 2025.11.19 LG ELECTRONICS INC
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  • EP4651480A1 patent drawingFigure 3

AI summary

An image encoding/decoding method and apparatus are provided. The image decoding method according to the present disclosure comprises the steps of: determining an intra prediction mode of the current block; and generating a prediction block of the current block by performing intra prediction on the basis of the determined intra prediction mode, wherein the intra prediction may be restricted to be performed by using only reference samples within a predetermined range from among available reference samples of the current block.