Spherical Neighbor De-blocking for 360 VR Projection Frames
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Solution Overview
Problem
Conventional de-blocking filters are ineffective in addressing image content discontinuities at picture boundaries and face edges in omnidirectional video content for 360-degree virtual reality projections, leading to degraded picture quality.
Innovation Solution
A spherical neighbor-based de-blocking method is employed, where a de-blocking filter identifies and utilizes spherical neighboring blocks to selectively apply de-blocking filters to block edges at image content discontinuity edges and picture boundaries, using type-specific filter processes to improve pixel continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional de-blocking filter is used on projection-based frames, then blocky artifacts within continuous image regions can be reduced, but image content discontinuities at picture boundaries and face edges cannot be properly handled
Solution Approach 1:
The patent applies different de-blocking filter processes based on the local characteristics of block edges. Type 1 filter process is applied to block edges within continuous image regions, while type 2 filter process is applied to block edges at image content discontinuities. This local differentiation allows the system to address blocky artifacts in continuous regions without compromising the handling of discontinuities at boundaries.
Solution Approach 2:
The patent segments the de-blocking filtering process into two distinct types based on the location and characteristics of block edges. By dividing the filtering approach into type 1 (for continuous regions) and type 2 (for discontinuous regions), the system can apply appropriate filtering strategies to different parts of the image, thereby resolving the contradiction between reducing blocky artifacts and preserving discontinuity information.
2Object-affected harmful factors
If de-blocking is applied to all block edges to reduce blocky artifacts, then picture quality within continuous regions improves, but seam artifacts at picture boundaries and face edges are exacerbated
Solution Approach 1:
The patent implements local quality by determining the type of block edge (continuous or discontinuous) and applying the appropriate filter process accordingly. This prevents the uniform application of de-blocking filters that would otherwise create seam artifacts at boundaries while still effectively reducing blocky artifacts in continuous regions.
Solution Approach 2:
The patent converts the potentially harmful effect of applying de-blocking filters at discontinuities (which would create seam artifacts) into a benefit by introducing a classification mechanism. The type determination process identifies discontinuous edges and applies a specialized filter process that eliminates blocky artifacts without creating seam artifacts, thus turning a potential harm into a beneficial outcome.
3Reliability
If a specialized de-blocking method for discontinuities is implemented, then picture quality at boundaries improves, but processing complexity increases
Solution Approach 1:
The patent segments the filtering process into two distinct types with clear decision criteria. The type determination step classifies block edges into type 1 (continuous) or type 2 (discontinuous), allowing the system to apply the appropriate filter process. This segmentation manages complexity by providing a structured approach rather than a monolithic complex algorithm.
Solution Approach 2:
The patent changes the parameter of filter process type based on the characteristics of the block edge. By using parameter changes (switching between type 1 and type 2 filter processes), the system adapts to different image regions without requiring a completely complex new algorithm, thereby managing processing complexity while improving boundary handling.
Data Source
AI summary
A de-blocking method is applied to a reconstructed projection-based frame having a first projection face and a second projection face, and includes obtaining a first spherical neighboring block for a first block with a block edge to be de-blocking filtered, and selectively applying de-blocking to the block edge of the first block for at least updating a portion of pixels of the first block. There is image content discontinuity between a face boundary of the first projection face and a face boundary of the second projection face. The first block is a part of the first projection face, and the block edge of the first block is a part of the face boundary of the first projection face. A region on a sphere to which the first spherical neighboring block corresponds is adjacent to a region on the sphere from which the first projection face is obtained.