Intra Prediction Interpolation Filters for Lower-Bitrate Image Coding

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Solution Overview

Problem

The increasing demand for high-resolution and high-quality images leads to higher transmission and storage costs due to increased bit rates, necessitating improved image encoding/decoding efficiency and reduced memory usage for interpolation filter coefficients.

Innovation Solution

An image encoding/decoding method that adaptively determines an interpolation filter based on intra prediction mode, using a 6-tap cubic filter for improved efficiency and reduced memory usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If high-resolution and high-quality images are transmitted and stored, then image quality is improved, but transmission costs and storage costs increase due to increased bit rate

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

Solution Approach 1:

The patent applies parameter changes by adaptively selecting interpolation filter types (e.g., 4-tap cubic filter, 6-tap cubic filter, 8-tap cubic filter, Gaussian filter) based on intra prediction modes. This adaptive parameter selection optimizes the balance between image quality and bit rate, reducing transmission and storage costs while maintaining high-quality image reconstruction through optimized filtering parameters

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If multiple interpolation filter types are stored to handle different intra prediction modes, then encoding flexibility is improved, but memory space waste increases

Engineering Contradiction:
Improveencoding flexibilityVSAvoidmemory space for interpolation filter coefficients
Core Design Contradiction:
Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent implements dynamics by making the interpolation filter type adaptive and variable based on the intra prediction mode. Instead of storing all filter types simultaneously, the system dynamically selects and stores only the necessary filter coefficients according to the specific intra prediction mode being used, thereby maintaining encoding flexibility while reducing memory space requirements

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent applies local quality by using different interpolation filter types for different intra prediction modes. Each mode receives the appropriate filter type locally optimized for its characteristics, rather than using a universal filter for all modes. This approach maintains high encoding flexibility while reducing the total memory space needed, as only the required filter coefficients for each specific mode are stored

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP4648417A1Image encoding/decoding method based on intra prediction, method for transmitting bitstream, and recording medium storing bitstream
Publication Date: 2025.11.12 LG ELECTRONICS INC
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AI summary

An image encoding/decoding method and apparatus are provided. The image decoding method according to the present disclosure comprises the steps of: generating a residual block for the current block; generating a prediction block for the current block on the basis of an intra prediction mode; and reconstructing the current block on the basis of the residual block and the prediction block, wherein the prediction block is generated further on the basis of an interpolation filter applied to a reference sample, the interpolation filter is adaptively determined on the basis of the intra prediction mode, and the interpolation filter may be determined to be a 6-tap cubic filter on the basis of the intra prediction mode being a template-based intra mode derivation (TIMD)-based directional intra prediction mode.