Adaptive Deblocking Filter for Inter-Predicted Transform Boundaries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional deblocking filters fail to effectively address discontinuities at edges between transform/coding blocks, particularly those using inter prediction, leading to visible artifacts in video coding, especially when sub block transform (SBT) is employed.
Innovation Solution
Implement a deblocking filter that considers and filters boundaries between transform blocks using inter prediction, especially for chroma samples, by determining a boundary strength parameter and applying filtering processes to reduce artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional deblocking filters are used, then processing is simple, but blocking artifacts remain visible at transform block boundaries
Solution Approach 1:
The patent applies different filtering strengths (boundary strength parameters) to different block boundaries based on their specific characteristics. Instead of uniform filtering, the system determines BS values of 0, 1, or 2 for each boundary based on factors like block size, transform type, and prediction mode, thereby achieving localized artifact reduction while maintaining overall image quality.
Solution Approach 2:
The filtering process dynamically adjusts boundary strength parameters based on real-time analysis of block characteristics. The system evaluates multiple factors (block size, transform coefficients, prediction mode) to determine appropriate filtering intensity for each boundary, making the filter adaptive rather than static.
2Manufacturing precision
If deblocking filtering is applied to all boundaries, then artifact reduction is maximized, but processing complexity and time increase
Solution Approach 1:
The patent applies filtering selectively rather than universally. By using boundary strength parameters that can be set to 0 (no filtering), 1 (weak filtering), or 2 (strong filtering), the system applies filtering only where necessary and to the appropriate degree, avoiding unnecessary processing on boundaries that don't require artifact reduction.
Solution Approach 2:
The system changes the filtering parameter (boundary strength) based on the specific characteristics of each boundary. By adjusting the BS parameter according to block size, transform type, and prediction mode, the system optimizes filtering intensity to match actual artifact severity, reducing processing time while maintaining effectiveness.
3Productivity
If sub block transform is used, then coding efficiency improves, but discontinuities and artifacts at transform boundaries increase
Solution Approach 1:
The patent applies deblocking filtering as a preliminary correction measure after sub block transform coding. By detecting discontinuities at transform boundaries and applying appropriate filtering (BS=1 or BS=2) before final reconstruction, the system preemptively counteracts the artifact-generating effect of fine-grained transform partitioning.
Data Source
AI summary
A deblocking method, for deblocking a transform block boundary within a coding block in an image encoding and/or an image decoding is provided, where the coding block comprising transform blocks is coded in inter prediction mode and the transform blocks comprises a first transform block and a second transform block. The method comprises: determining, when the boundary between the first transform block and the second transform block is a transform block boundary and at least one of the first transform block and the second transform block has one or more non-zero transform coefficients, a value of a BS parameter for the boundary between the first transform block and the second transform block to be a first value; and performing de-blocking filtering process to the boundary between the first transform block and the second transform block at least based on the value of the boundary strength parameter.