Chroma Transform Size Limits for IBC Image Coding

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The increasing demand for high-resolution and high-quality images leads to a significant increase in transmission and storage costs due to the increased amount of information, necessitating high-efficient image compression technology.

Innovation Solution

An image encoding/decoding method that limits the maximum transform size of a chroma component coding block, utilizing intra block copy (IBC) prediction, and generates a bitstream for efficient transmission and storage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the transform size of chroma component coding blocks is increased to improve compression efficiency, then the compression ratio improves, but the encoding/decoding complexity and processing overhead increase

Engineering Contradiction:

Improvecompression efficiencyVSAvoidencoding/decoding complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by dynamically adjusting the transform block size based on the chroma component type. Specifically, it sets the maximum transform block size to 32×32 for 4:2:0 chroma format and 16×16 for 4:2:2 chroma format, optimizing the balance between compression efficiency and processing complexity for different color sampling configurations

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements local quality by applying different transform block size constraints to different chroma component types within the same image data. The encoding apparatus selectively determines transform block sizes based on whether the chroma component is 4:2:0 or 4:2:2, allowing optimized processing characteristics for each component type rather than using a uniform approach

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If high-resolution images are transmitted without compression, then image quality is preserved, but transmission cost and storage cost increase significantly

Engineering Contradiction:

Improveimage qualityVSAvoidtransmission data volume

Core Design Contradiction:

Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The patent applies segmentation by separating the processing of luma and chroma components with different transform block size constraints. By segmenting the chroma component processing based on color format (4:2:0 vs 4:2:2), the patent achieves efficient compression while preserving perceptual image quality, reducing transmission data volume without sacrificing critical visual information

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS12375721B2Image encoding/decoding method and device using maximum transform size restriction of chroma component encoding block, and method for transmitting bitstream

Publication Date: 2025.07.29 NOKIA TECHNOLOGIES OY

AI summary

An image encoding/decoding method and apparatus are provided. An image decoding method performed by an image decoding apparatus may include determining a prediction mode of a current block, generating a prediction block of the current block based on intra block copy (IBC) prediction mode information, based on the prediction mode of the current block being an IBC prediction mode, determining a size of a transform block of the current block based on a color component of the current block, generating a residual block of the current block based on the size of the transform block; and reconstructing the current block based on the prediction block and the residual block of the current block.