Chroma-Aware Quantization in Image Encoding Without Transform Processing

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing image encoding methods, such as HEVC and VVC, face inefficiencies in encoding artificial images due to unnecessary increases in code amount when using quantization parameters less than 4, leading to suboptimal image quality and increased data size.

Innovation Solution

Adaptive correction of quantization parameters by determining whether to perform transform processing on chroma components, using a reference value as a quantization parameter when transform processing is not performed, thereby reducing unnecessary code increases.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a quantization parameter less than 4 is used in encoding without transform processing, then gradations are increased and image quality is improved, but the amount of code increases unnecessarily

Engineering Contradiction:

Improveimage qualityVSAvoidamount of code

Core Design Contradiction:

Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The patent dynamically adjusts the quantization parameter based on the transform processing status. When transform processing is not performed on chroma components, the quantization parameter is corrected to be 4 or greater, preventing unnecessary code increase while avoiding image quality degradation. This parameter adaptation resolves the contradiction by making the quantization parameter conditional on the processing mode.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If transform processing is performed on chroma component, then encoding efficiency is improved, but a first quantization parameter smaller than reference value may cause unnecessary code increase

Engineering Contradiction:

Improveencoding efficiencyVSAvoidamount of code

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The patent implements a feedback mechanism where the quantization parameter for chroma components is adjusted based on the transform processing status. The determination unit checks whether transform processing is performed, and the encoding unit adapts the quantization parameter accordingly. This feedback loop ensures that when transform processing is not performed, the quantization parameter is corrected to prevent unnecessary code increase, thus resolving the contradiction between encoding efficiency and code amount.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS20250330578A1Image encoding device, image encoding method, image decoding device, image decoding method, and non-transitory computer-readable storage medium

Publication Date: 2025.10.23 CANON KK

AI summary

The block to be encoded is encoded using a first quantization parameter corresponding to a coefficient of each color component in the block to be encoded when it is determined that orthogonal transform processing is to be performed on the coefficient of each color component in the block to be encoded, and the block to be encoded is encoded using a second quantization parameter obtained by correcting the first quantization parameter when it is determined that orthogonal transform processing is not to be performed on the coefficient of each color component in the block to be encoded. A predetermined determination based on the first quantization parameter and a predetermined value is performed, and the second quantization parameter is derived by correcting the first quantization parameter in accordance with a determination result of the predetermined determination.