Intra Prediction Mode Decoding Using MPM Group

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Solution Overview

Problem

The existing H.264 image compression technique has low encoding and decoding efficiency for intra prediction modes, as it does not effectively utilize the directionalities of intra prediction modes from neighboring blocks, leading to suboptimal compression of image data.

Innovation Solution

An intra prediction mode decoding method that creates an MPM group using valid intra prediction modes from neighboring blocks, adding additional modes based on their directionalities, and assigns lower mode numbers to non-directional modes to reduce encoding information, thereby enhancing compression and decompression efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If intra prediction mode is encoded regardless of directivity of neighboring blocks, then encoding is performed uniformly, but encoding efficiency is low

Engineering Contradiction:
Improveencoding efficiencyVSAvoidamount of information for encoding
Core Design Contradiction:
ProductivityVSLoss of information

Solution Approach 1:

The patent changes the parameter of intra prediction mode encoding by introducing an MPM group indicator that adapts the encoding parameters based on the directivity characteristics of neighboring blocks. When neighboring blocks have directional modes, the encoder uses a reduced set of modes (MPM group) with fewer bits, while non-directional modes use the full mode set, thereby optimizing the balance between encoding efficiency and information representation.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by treating different regions (neighboring blocks) with different encoding strategies. The MPM group is constructed based on the specific characteristics of adjacent blocks, allowing the encoding to adapt locally to the image content's directional properties rather than applying a uniform encoding approach across all blocks.

Inventive Principle:
Principle #3Local quality

2Productivity

If number of intra prediction modes increases to enhance encoding efficiency of residual block, then residual block encoding efficiency is improved, but intra prediction mode encoding complexity increases

Engineering Contradiction:
Improveresidual block encoding efficiencyVSAvoidintra prediction mode encoding complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent segments the intra prediction modes into two distinct groups: the MPM group (containing modes likely to be used based on neighboring block characteristics) and the remaining modes. This segmentation allows the encoder to handle the more probable modes with simplified encoding (using the MPM group indicator) while reserving the full mode set for less probable cases, thereby reducing overall encoding complexity while maintaining efficiency.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces dynamic adaptivity by making the intra prediction mode encoding process dependent on the characteristics of neighboring blocks. The MPM group is dynamically constructed based on the directivity of adjacent blocks, allowing the encoding complexity to adapt to the local image content. This dynamic approach ensures that the encoding complexity is minimized when possible (using the smaller MPM group) while maintaining the ability to represent all necessary modes when needed.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP2945380B1Method and apparatus for decoding intra prediction mode
Publication Date: 2021.11.17 INNOTIVE LTD
  • EP2945380B1 patent drawingFigure 1
  • EP2945380B1 patent drawingFigure 2
  • EP2945380B1 patent drawingFigure 3

AI summary

A method for decoding an intra prediction mode according to the present invention comprises: restoring an intra prediction mode group indicator and a prediction mode index; creating an MPM group comprising three intra prediction modes using valid intra prediction modes of blocks left and above the current block; and selecting, as the intra prediction mode of the current block, an intra prediction mode from within the group corresponding to the prediction mode indicator and the prediction mode index, wherein the non-directional intra prediction modes have smaller intra prediction mode numbers than the directional intra prediction modes. Therefore, the encoding efficiency of the intra prediction mode can be improved by using modes having a high probability of being identical to the intra prediction mode of the current block on the basis of the valid intra prediction modes of blocks left and above the current block. Additionally, the amount of information needed to encode the intra prediction mode of the current block can be reduced by configuring the method so that the non-directional modes are assigned indices having low occurrence frequencies.