Deblocking Filter Strength Determination Using Comprehensive Flatness
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Solution Overview
Problem
Deblocking filters in video encoding and decoding fail to achieve expected results due to improper judgment conditions for determining filter strength, leading to inadequate or excessive filtering, which affects the subjective and objective quality of the picture.
Innovation Solution
A method that determines filter strength by calculating the comprehensive flatness of pixel groups across filtering boundaries, using one-sided flatness values and adjusting thresholds based on the average quantization parameter, to ensure more accurate filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the prior art judgment conditions for determining filter strength are used, then the deblocking filter can be applied to eliminate blockiness, but the filter strength is either insufficient for boundaries that need filtering or excessive for boundaries that should not be filtered
Solution Approach 1:
The patent changes the parameters used for filter strength determination from simple boundary characteristics to comprehensive pixel value difference states. By calculating one-sided flatness values (FL and FR) that consider multiple pixel differences (abs(p0-p1), abs(q0-q1), abs(p0-p2), abs(q0-q2)) and combining them into comprehensive flatness (FS=FL+FR), the system adapts the filter strength parameter dynamically based on the actual pixel variations, thereby improving filtering accuracy without excessive complexity
Solution Approach 2:
The patent applies local quality by treating different regions around the filtering boundary with different analysis depths. The one-sided flatness calculation examines pixel values at different distances from the boundary (P0, P1, P2 on one side and Q0, Q1, Q2 on the other side), allowing the filter strength to be precisely adapted to local image characteristics. This ensures that each boundary is filtered according to its specific local properties rather than using a uniform approach
2Manufacturing precision
If the filter strength is increased to ensure adequate filtering of all boundaries, then blockiness is reduced, but unnecessary filtering is applied to boundaries that should not be filtered
Solution Approach 1:
The patent implements partial action by calculating a comprehensive flatness value FS that ranges from 0 to 6, and using this to selectively apply filter strengths from 0 to 4 only where needed. The filtering is partially applied based on the calculated FS value - boundaries with low flatness (FS<3) receive no filtering (strength=0), while boundaries with high flatness (FS≥3) receive appropriate filtering strength. This prevents excessive filtering by making the filtering action conditional and proportional to the actual blockiness present
3Object-generated harmful factors
If the filter strength is decreased to avoid excessive filtering, then natural boundaries are preserved, but boundaries that need filtering remain blocky
Solution Approach 1:
The patent applies dynamics by making the filter strength adaptive rather than static. The filter strength dynamically adjusts based on the calculated comprehensive flatness FS, which itself is dynamically determined by the actual pixel value differences in the filter pixel group. The system continuously evaluates the local image characteristics and adjusts the filtering intensity accordingly, ensuring that boundaries with significant blockiness receive stronger filtering while natural boundaries receive minimal or no filtering
Data Source
AI summary
The present application provides methods, systems, devices and computer-readable mediums for deblocking filter. A method of the present application comprises: determining a filtering boundary, and then determining a filter pixel group based on the filtering boundary; determining a filter strength of the filter pixel group, comprising: parsing separately a pixel value difference states of pixel points on both sides of the filtering boundary in the filter pixel group to obtain two one-sided flatness FL and FR; calculating a comprehensive flatness FS of the filter pixel group, wherein FS=FL+FR; calculating the filter strength according to FS; filtering calculation of pixel points included in the filter pixel group according to the filter strength. Compared with the prior art, the method of the embodiment of the present invention fully considers the pixel value change state of the pixel points on both sides of the filtering boundary, so that a more reasonable filter strength judgment condition is adopted when determining the filter strength of the filter pixel group, thereby finally obtaining a more realistic deblocking filter result.