Dependent Random-Access Picture Decoding With Zero-Recovery GDR

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Solution Overview

Problem

The increasing demand for high-resolution and high-quality images leads to a significant increase in the amount of transmitted and stored information, resulting in higher costs for transmission and storage, necessitating the need for more efficient image compression technologies.

Innovation Solution

An image encoding/decoding method and apparatus that utilizes a dependent random access point picture, specifically a gradual decoding refresh (GDR) picture with a zero recovery point, to enhance encoding/decoding efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If high-resolution and high-quality images are transmitted and stored, then image quality is improved, but transmission cost and storage cost increase

Engineering Contradiction:
Improveimage qualityVSAvoidamount of transmitted information
Core Design Contradiction:
Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The image sequence is segmented into different types of pictures (I pictures, P pictures, B pictures) with different compression levels and reference relationships. I pictures are fully decoded and stored, while P and B pictures use differential encoding relative to reference pictures, reducing the amount of data that needs to be transmitted and stored while maintaining image quality.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Reference pictures (I pictures) are decoded and stored in advance before subsequent pictures are processed. This preliminary action allows subsequent P and B pictures to use these pre-decoded reference pictures for differential encoding, reducing the amount of data that needs to be transmitted and stored.

Inventive Principle:
Principle #10Preliminary action

2Ease of operation

If random access to picture data is enabled, then access flexibility is improved, but decoding complexity increases

Engineering Contradiction:
Improverandom access capabilityVSAvoiddecoding complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The bitstream is segmented into access units with clear boundaries, each containing picture data and associated metadata. This segmentation allows the decoder to randomly access specific access units without needing to decode the entire bitstream, reducing decoding complexity while maintaining random access capability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Picture parameter sets and sequence parameter sets act as intermediaries that contain decoding parameters and metadata. These intermediary data structures allow the decoder to quickly parse and understand picture data without full decoding of previous frames, enabling random access with reduced complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4586609A1Method and device for image encoding/decoding based on dependent random-access point picture, and method for bitstream transmission
Publication Date: 2025.07.16 LG ELECTRONICS INC
  • EP4586609A1 patent drawingFigure 1
  • EP4586609A1 patent drawingFigure 2
  • EP4586609A1 patent drawingFigure 3

AI summary

A method and a device for image encoding/decoding are provided. An image decoding method according to the present disclosure may comprise the steps of: in response to a random-access request for a first picture, acquiring a second picture which is associated with the first picture and has been decoded before the first picture; and decoding the first picture by referring to the second picture, wherein the first picture is a dependent random-access point picture, and the second picture is gradual coding refresh (GDR) picture having a zero-recovery point picture.