Palette Mode Coding for Luma and Chroma Components

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Solution Overview

Problem

Current video coding technologies face inefficiencies in applying palette mode coding, particularly when dealing with non-square coding units and separate coding of luma and chroma components, as they often require complex prediction and encoding processes that can lead to increased complexity and reduced coding efficiency.

Innovation Solution

The proposed method enables joint or separate palette mode coding for luma and chroma components using a quadtree plus binary tree structure, allowing for flexible partitioning and efficient coding by determining the appropriate coding mode and predictor lists based on the characteristics of the image, including the use of joint or separate palettes and adaptive scan directions for non-square coding units.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If palette mode coding is applied to both luma and chroma components with separate CU structures, then coding efficiency is improved, but device complexity increases due to complex prediction and encoding processes

Engineering Contradiction:
Improvecoding efficiencyVSAvoidencoding complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent merges the prediction processes of luma and chroma components by using the luma prediction block to derive chroma prediction blocks. This combining approach reduces the number of independent prediction operations needed, thereby lowering encoding complexity while maintaining coding efficiency through the shared prediction mechanism.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The luma prediction block serves as an intermediary to generate chroma prediction blocks. Instead of independently processing chroma prediction, the system uses the already-computed luma prediction as a mediator, which simplifies the overall prediction process and reduces computational complexity while preserving color information accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If separate CU structures are used for luma and chroma components, then adaptability is improved, but device complexity increases

Engineering Contradiction:
Improvepartitioning flexibilityVSAvoidprocessing complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments the video data into luma and chroma components with separate CU structures, allowing independent partitioning of each component. This segmentation enables flexible adaptation to different image characteristics while the shared prediction mechanism keeps processing complexity manageable by reusing computation across components.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3731527B1Method and apparatus of palette mode coding for colour video data
Publication Date: 2022.10.19 HFI INNOVATION INC
  • EP3731527B1 patent drawingFigure 1~2
  • EP3731527B1 patent drawingFigure 3~4
  • EP3731527B1 patent drawingFigure 5~6

AI summary

Methods and apparatus for a coding system using palette mode coding for colour video are disclosed. According to method, when the palette mode is enabled, separate coding of luma and chroma components is disabled or if separate coding of luma and chroma components, the palette mode is disabled. According to another method, when the palette mode is enabled for the current image, palette mode coding is only applied to the luma blocks and non-palette mode coding is applied to the chroma blocks. According to yet another method, palette mode coding is applied to the luma blocks using luma palettes if the palette mode is selected for the luma blocks and palette mode coding applying to the chroma blocks using chroma palettes if the palette mode is selected for the chroma blocks. According to yet another method, the scan direction for a non-square CU depends on the shape of the non-square.