Arithmetic Coding Context Selection Without Coefficient Counting

Solution Overview

Problem

Conventional image coding methods, such as those based on the HEVC standard, require counting coefficients with absolute values greater than a threshold, leading to increased processing and potential deterioration in coding efficiency.

Innovation Solution

The proposed method selects a context for arithmetic coding based on whether the immediately-prior coefficient block includes a coefficient with an absolute value greater than a threshold, reducing processing requirements while maintaining coding efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the number of coefficients with absolute values greater than a threshold is counted to select context, then coding efficiency is improved, but processing amount increases

Engineering Contradiction:

Improvecoding efficiencyVSAvoidprocessing amount

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent extracts only the essential information needed for context selection - specifically whether the immediately-prior coefficient block contains any coefficient with absolute value greater than a threshold. This eliminates the need to count all such coefficients, reducing processing complexity while maintaining the ability to select appropriate contexts for arithmetic coding.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent performs preliminary determination of whether a threshold-exceeding coefficient exists in the immediately-prior block before proceeding with full context selection. This preliminary check allows the system to quickly identify cases where simplified context selection can be applied, reducing overall processing burden while preserving coding efficiency.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the number of coefficients with absolute values greater than a threshold is counted to select context, then coding efficiency is improved, but processing complexity increases

Engineering Contradiction:

Improvecoding efficiencyVSAvoidprocessing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts only the essential information needed for context selection - specifically whether the immediately-prior coefficient block contains any coefficient with absolute value greater than a threshold. This eliminates the need to count all such coefficients, reducing processing complexity while maintaining the ability to select appropriate contexts for arithmetic coding.

Inventive Principle:

Principle #2Taking out (Extraction)

3Measurement precision

If full context selection based on coefficient counting is performed, then coding precision is improved, but processing time increases

Engineering Contradiction:

Improvecoding precisionVSAvoidprocessing time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs preliminary determination of whether a threshold-exceeding coefficient exists in the immediately-prior block before proceeding with full context selection. This preliminary check allows the system to quickly identify cases where simplified context selection can be applied, reducing overall processing burden while preserving coding efficiency.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies partial context selection based on a simplified criterion (presence rather than count of threshold-exceeding coefficients). This partial approach is sufficient to capture the essential patterns needed for effective arithmetic coding, achieving adequate coding precision without the time cost of complete coefficient counting.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentEP2866444B1Image encoding method, image decoding method, image encoding device, image decoding device

Publication Date: 2022.04.13 SUN PATENT TRUST

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AI summary

An image coding method using arithmetic coding. The method includes: performing arithmetic coding on a first flag (greater1_flag) that indicates whether or not an absolute value of a target coefficient in a target coefficient block is greater than 1 (S701); and performing arithmetic coding on a second flag (greater2_flag) that indicates whether or not the absolute value is greater than 2 (S702). In the arithmetic coding on the first flag and the arithmetic coding on the second flag, it is determined whether or not an immediately-prior coefficient block that has been coded immediately prior to the target coefficient block includes a coefficient having an absolute value greater than a threshold value (S711). Based on a result of the determination, respective contexts to be used in the arithmetic coding on the first and second flags are selected (S712).