Backward Warping View Synthesis Prediction Using Neighboring Blocks
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Solution Overview
Problem
Conventional multiview video coding methods, such as those based on forward warping, face increased complexity and are not suitable for backward warping-based view synthesis prediction due to the requirement of depth-first coding, which restricts the use of depth coding tools that need to access the corresponding texture component.
Innovation Solution
The method employs backward warping for view synthesis prediction by deriving a depth block from neighboring blocks' motion or disparity vectors, allowing the depth component to be coded after the texture component and enabling block-based reference generation without depth-first coding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If forward warping based view synthesis prediction is used, then high fidelity is achieved, but codec complexity significantly increases
Solution Approach 1:
The patent inverts the conventional forward warping approach by using backward warping. Instead of projecting texture from reference view to current view (forward), the method projects texture from current view to reference view (backward), then uses the derived depth block to warp the reference view texture to generate the prediction. This inversion reduces codec complexity while maintaining acceptable fidelity.
2Device complexity
If backward warping based view synthesis prediction is used, then codec complexity is reduced, but depth-first coding is required which restricts use of depth coding tools
Solution Approach 1:
The patent performs preliminary action by deriving the depth block for the current block before coding the depth component. The depth block is derived from neighboring blocks' motion/disparity vectors and reference depth images, enabling backward warping to be performed during texture coding without requiring depth-first coding order. This preliminary derivation allows flexible depth coding tool selection.
Solution Approach 2:
The patent introduces an intermediary mechanism - the derived depth block - that acts as a bridge between the texture coding process and depth coding tools. By deriving this intermediate depth representation from neighboring blocks, the system enables backward warping during texture coding while maintaining independence from depth coding order, thus serving as a mediator that resolves the contradiction between complexity reduction and tool accessibility.
3Ease of operation
If depth component is coded before texture component (depth-first coding), then backward warping can be performed, but flexibility in coding tool selection is lost
Solution Approach 1:
The patent performs the depth block derivation action preliminarily, before the depth component coding is completed. By deriving the depth block from already-coded neighboring blocks during the texture coding phase, the method enables backward warping capability without imposing depth-first coding constraints, thus maintaining coding tool flexibility.
Data Source
AI summary
Videos of a scene are processed for view synthesis. The videos are acquired by corresponding cameras arranged so that a view of each camera overlaps with the view of at least one other camera. For each current block, motion or disparity vector is obtained from neighboring blocks. A depth block is based on a corresponding reference depth image and the motion or disparity vector. A prediction block is generated based on the depth block using backward warping. Then, predictive coding for the current block using the prediction block.