Intra Block Copy Predictor Search Across Spatial Subdivisions

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Solution Overview

Problem

The Intra Block Copy (IBC) mode in the HEVC standard is less effective for video data encoding when slices or tiles are used, leading to reduced coding gains in screen content sequences compared to other sequences.

Innovation Solution

The method allows the predictor block for Intra Block Copy mode to be located in any previously decoded spatial subdivision, including outside the current spatial subdivision, enhancing coding/decoding efficiency and flexibility by using motion vectors associated with blocks of pixels in subdivided images.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If slices or tiles are used in the images of the video data, then parallel processing and memory usage are improved, but IBC coding gains are reduced

Engineering Contradiction:

Improveparallel processing efficiencyVSAvoidcoding gain

Core Design Contradiction:

ProductivityVSLoss of information

Solution Approach 1:

The image is divided into slices and tiles for parallel processing, but the invention allows IBC prediction to cross these segmentation boundaries by extending the search area to previously decoded spatial subdivisions, thus maintaining coding efficiency while preserving parallel processing benefits

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention extends the IBC search from the traditional 2D causal area within the current slice/tile to include previously decoded spatial subdivisions in additional spatial dimensions, allowing predictor blocks to be found outside the immediate causal area while maintaining decoding efficiency

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Device complexity

If the predictor block search area is restricted to the current spatial subdivision, then decoding complexity is reduced, but coding efficiency is worsened

Engineering Contradiction:

Improvedecoding complexityVSAvoidcoding efficiency

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The invention applies different search area rules to different spatial subdivisions: some subdivisions allow cross-boundary prediction while others maintain restricted search areas, optimizing the balance between coding efficiency and decoding complexity for each region

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The search area for IBC prediction is made dynamic based on the decoding status of spatial subdivisions, allowing the predictor block to be found in any previously decoded spatial subdivision rather than a fixed causal area, adapting to the actual decoding progress

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS10178405B2Enhanced coding and decoding using intra block copy mode

Publication Date: 2019.01.08 CANON KK

AI summary

A decoding method wherein a motion vector is associated with a block of pixels of a current image,wherein the image is subdivided into spatial subdivisions,wherein the block of pixels belongs to a current spatial subdivision and is to be predicted using an Intra Block Copy mode, using a predictor block of pixels of the image designated by the motion vector, andwherein the predictor block designated by the motion vector may belong to any one of previously decoded spatial subdivisions in the current image.Embodiments provide enhancements to the Intra Block Copy Mode of the HEVC standard.