Multi-Line Intra Interpolation Filters for Edge-Aware Prediction
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Solution Overview
Problem
Existing video coding technologies, such as HEVC and VVC, apply the same cubic and Gaussian filters to all reference lines in multi-line intra prediction, which is not desirable for areas with edges and smooth image regions.
Innovation Solution
A method and device for selecting different types of interpolation filters based on the reference line index, applying edge preserving filters to non-zero reference lines and edge smoothing filters to zero reference lines, and adjusting filter coefficients and taps based on block characteristics and intra prediction modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the same cubic and Gaussian filters are applied to all reference lines in multi-line intra prediction, then the implementation is simple and uniform, but the prediction accuracy deteriorates for areas with edges and smooth image regions
Solution Approach 1:
The patent applies different filtering strategies to different reference lines based on their characteristics. Specifically, edge-preserving filters are applied to reference lines that are likely to contain edge information, while smoothing filters are applied to reference lines from smooth regions. This local differentiation of filter types resolves the contradiction by improving prediction accuracy for both edge and smooth regions without requiring a completely complex system, as the filter selection is based on simple reference line identification.
2Manufacturing precision
If different types of interpolation filters are selected based on reference line index, then edge preservation and smoothing are enhanced, but the computational complexity and processing time increase
Solution Approach 1:
The patent performs filter selection in advance based on the reference line index before the actual interpolation process. By determining which filter type to apply for each reference line beforehand, the system avoids dynamic filter selection during processing, thereby reducing computational overhead and processing time while still achieving enhanced edge preservation and smoothing effects.
3Manufacturing precision
If multiple filter types are applied to different reference lines, then prediction quality improves for both edge and smooth regions, but the device complexity and implementation difficulty increase
Solution Approach 1:
The patent manages the complexity of multiple filter types by parameterizing the filter selection process. The reference line index serves as a key parameter that determines which filter type to apply. This parameter-based approach allows the system to handle multiple filter types systematically, improving prediction quality for both edge and smooth regions while keeping the implementation manageable through clear parameter-driven logic.
Data Source
AI summary
A method and apparatus for selecting an intra interpolation filter for multi-line intra prediction based on a reference line index for decoding a video sequence includes identifying a set of reference lines associated with a coding unit. A first type of interpolation filter is applied to reference samples included in a first reference line, of the set of reference lines, that is adjacent to the coding unit to generate a first set of prediction samples based on the first reference line being associated with a first reference line index. A second type of interpolation filter is applied to reference samples included in a second reference line, of the set of reference lines, that is non-adjacent to the coding unit to generate a second set of prediction samples based on the second reference line being associated with a second reference line index.