Pyramid Projection Padding for 360 VR Artifact Reduction
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Solution Overview
Problem
The delivery of high-quality 360-degree virtual reality content is hindered by the high bitrate required for omnidirectional image/video content, leading to image quality degradation due to improper design of 360 VR projection layouts, which introduces artifacts during encoding and conversion.
Innovation Solution
The proposed method involves creating a pyramid projection layout with boundary padding and edge padding to reduce artifacts, using a padding circuit to generate padding regions that connect with projection faces and isolate boundaries, and applying smooth filtering to non-main view projection faces to improve coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-resolution omnidirectional video content is transmitted, then image quality is improved, but bitrate requirement increases
Solution Approach 1:
The omnidirectional video content is divided into multiple projection faces (e.g., 8 faces for cubic projection) that can be independently encoded and transmitted. This segmentation allows for targeted compression strategies on each face while maintaining overall image quality, reducing the total bitrate requirement compared to transmitting the complete omnidirectional content as a single high-resolution stream.
2Quantity of substance
If projection-based frame encoding is applied, then bitrate is reduced, but artifacts are introduced
Solution Approach 1:
Padding regions are pre-generated and inserted between adjacent projection faces before the encoding process. This preliminary action ensures that when compression artifacts occur during encoding, they are isolated within individual projection faces and do not propagate across face boundaries, thereby maintaining image quality while still achieving bitrate reduction through compression.
Solution Approach 2:
Padding regions act as intermediary elements between adjacent projection faces. These padding regions serve as buffers that prevent the direct interaction and mutual contamination of artifacts from neighboring faces during encoding and conversion processes, thus preserving overall image quality while enabling efficient compression.
3Adaptability or versatility
If projection layout conversion is performed, then delivery flexibility is improved, but image quality degradation occurs
Solution Approach 1:
The padding regions are pre-inserted between projection faces before any layout conversion operations. This preliminary preparation ensures that when different projection layouts (e.g., cubic, spherical, equirectangular) are converted, the artifact isolation mechanism is already in place, preventing quality degradation during the conversion process while maintaining delivery flexibility across multiple formats.
Data Source
AI summary
An exemplary video processing method includes: receiving an omnidirectional content corresponding to a sphere; obtaining a plurality of projection faces from the omnidirectional content of the sphere according to a pyramid projection; creating at least one padding region; and generating a projection-based frame by packing the projection faces and the at least one padding region in a pyramid projection layout. The projection faces packed in the pyramid projection layout include a first projection face. The at least one padding region packed in the pyramid projection layout includes a first padding region. The first padding region connects with at least the first projection face, and forms at least a portion of one boundary of the pyramid projection layout.