Cube-Based Projection Padding for Video Artifact Reduction
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Solution Overview
Problem
Omnidirectional video content processing faces challenges in reducing bitrate due to high data requirements, leading to image quality degradation and artifacts at layout boundaries and face edges in projection-based frames, especially when using compact cube-based projection layouts without padding.
Innovation Solution
A method involving a cube-based projection layout with padding and face scaling, where padding regions and scaled projection faces are used to improve image quality by reducing discontinuities and maintaining the same frame size as compact layouts without padding, and a blending circuit for decoding to reconstruct pixel values by weighting decoded pixels from faces and padding regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a compact cube-based projection layout without padding is used, then the frame size is reduced and encoding efficiency is improved, but image quality deteriorates at layout boundaries and face edges due to discontinuities
Solution Approach 1:
The patent applies preliminary action by pre-scaling the projection faces before encoding and introducing padding regions around the faces. This preparatory scaling and padding arrangement resolves the discontinuity issues at boundaries before the actual encoding process, thereby maintaining both encoding efficiency and image quality at boundaries.
Solution Approach 2:
The patent applies local quality by introducing padding regions specifically at the boundaries and edges of projection faces, rather than uniformly across the entire frame. This localized approach addresses the image quality deterioration at critical boundary areas while maintaining the compact frame size and encoding efficiency of the overall structure.
2Loss of energy
If compression/encoding is applied to reduce bitrate, then data transmission efficiency is improved, but image quality degrades especially around layout boundaries and face edges
Solution Approach 1:
The patent performs preliminary scaling of projection faces and introduces padding regions before the compression/encoding process. This pre-processing ensures that discontinuities at boundaries are mitigated in advance, so that when compression is applied to reduce bitrate, the image quality at boundaries and edges is preserved better than without these preliminary measures.
Solution Approach 2:
The padding regions act as a cushioning mechanism that protects against the harmful effects of compression at boundaries. By introducing these padding regions beforehand, the patent creates a buffer that prevents the discontinuities from being exacerbated during the compression process, thereby maintaining image quality even when bitrate is reduced.
3Adaptability or versatility
If projection layout conversion is performed, then the omnidirectional content can be displayed in standard formats, but artifacts are introduced leading to image quality degradation
Solution Approach 1:
The patent applies local quality by introducing padding regions specifically at the boundaries and edges of projection faces during the layout conversion process. This localized treatment addresses the artifact generation at critical boundary areas during conversion, while maintaining the overall adaptability and versatility of the projection layout conversion for standard display formats.
Solution Approach 2:
The patent performs preliminary scaling and padding introduction before the final layout conversion. This pre-processing step prepares the projection faces in a way that minimizes artifact generation during the conversion process, thereby maintaining image quality while achieving display compatibility with standard formats.
Data Source
AI summary
A video processing method includes: obtaining a plurality of square projection faces from an omnidirectional content of a sphere according to a cube-based projection, scaling the square projection faces to generate a plurality of scaled projection faces, respectively, creating at least one padding region, generating a projection-based frame by packing the scaled projection faces and said at least one padding region in a projection layout of the cube-based projection, and encoding the projection-based frame to generate a part of a bitstream.