Chroma Deblocking Filter Control at Decoded Block Boundaries
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Solution Overview
Problem
Existing video coding systems, such as H.265/HEVC and proposed FVC, face challenges in appropriately applying deblocking filters to color difference components of decoded images due to reliance on luminance component information, leading to potential block distortion.
Innovation Solution
An image processing apparatus and method that determines deblocking filter application necessity for color difference components based on boundary strength calculated using color difference-related parameters, applying a deblocking filter to pixels near the block boundary according to the determination, and optionally using a stronger filter to reduce distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If boundary strength is calculated using only luminance component information, then the processing complexity is reduced and the system is simpler to implement, but the deblocking filter cannot be appropriately applied to color difference components leading to block distortion
Solution Approach 1:
The boundary strength calculation is segmented into two independent parts: one based on luminance component information and another based on color difference component information. This allows the system to maintain simplicity while improving accuracy by processing different color components separately with appropriate boundary strength values.
Solution Approach 2:
Different boundary strength values are assigned to different color components (luminance, Cr, Cb) based on their specific characteristics. The luminance component uses boundary strength calculated from luminance information, while color difference components use boundary strength calculated from their respective information, allowing each component to be processed with optimal quality.
2Device complexity
If the same deblocking filter is applied to both luminance and color difference components using luminance-based boundary strength, then the system complexity is reduced, but block distortion remains in color difference components
Solution Approach 1:
The boundary strength parameter is changed and differentiated for different color components. Instead of using a single boundary strength value derived from luminance for all components, the system calculates separate boundary strength values: bsY for luminance based on luminance information, and bsC for color difference components based on color difference information. This parameter differentiation eliminates block distortion while maintaining manageable system complexity.
3Manufacturing precision
If boundary strength calculation uses color difference related parameters, then the deblocking filter application accuracy for color difference components is improved, but the calculation complexity increases
Solution Approach 1:
The boundary strength calculation process is segmented into separate calculations for different color components. The color difference related parameters (Cb and Cr component information) are used specifically for calculating boundary strength for color difference components, not for all components. This segmentation improves accuracy for color difference components while limiting the increased complexity to only the necessary calculations.
Data Source
AI summary
An image processing apparatus is provided. The image processing apparatus includes a decoding unit configured to generate a decoded image by decoding a coded stream, a determination unit configured to adopt a block boundary of the decoded image as a target and determine deblocking filter application necessity with respect to color difference components of the decoded image based on boundary strength that is calculated using a color difference related parameter related to a color difference, and a filtering unit configured to apply a deblocking filter to color difference components of pixels located in a vicinity of the block boundary based on a determination result of the deblocking filter application necessity.