Image Encoding Chroma Quantization Adaptation for Transform Skipping

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 without improved compression.

Innovation Solution

Adaptive correction of quantization parameters for chroma components in image encoding and decoding processes, using a reference value when transform processing is not performed, to prevent unnecessary increases in code amount and maintain image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a quantization parameter smaller than 4 is used to increase gradations, then image quality after compression is improved, but the amount of code increases unnecessarily when transform processing is not performed

Engineering Contradiction:

Improveimage qualityVSAvoidamount of code

Core Design Contradiction:

Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The patent dynamically changes the quantization parameter based on whether transform processing is performed. When transform processing is skipped, the quantization parameter is adjusted to a value not smaller than 4, preventing unnecessary code increase while maintaining appropriate image quality. This parameter adaptation resolves the contradiction by making the quantization parameter conditional on the transform processing decision.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If transform processing is skipped for chroma component encoding, then encoding efficiency is improved, but using a small quantization parameter still increases code amount

Engineering Contradiction:

Improveencoding efficiencyVSAvoidcode amount

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The patent applies parameter changes by adjusting the quantization parameter specifically for chroma components when transform processing is skipped. The quantization parameter is set to a value not smaller than 4 in this condition, which prevents the code amount from increasing unnecessarily while maintaining encoding efficiency benefits from skipping transform processing.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12375642B2Image encoding device, image encoding method, image decoding device, image decoding method, and non-transitory computer-readable storage medium

Publication Date: 2025.07.29 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.