Adaptive Post-Deringing Filter for HD Image Transcoding
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Solution Overview
Problem
Existing image filtering methods are inadequate for effectively removing artifacts such as ringing noise from high-definition images during transcoding from MPEG-2 to H.264, leading to suboptimal picture quality and performance.
Innovation Solution
An image filtering system that detects edges to identify probable ringing artifacts, applies a low-pass filter to affected pixels, and blends the filtered pixels with original values using specific coefficients to produce a filtered image, effectively removing artifacts without introducing blurring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a strong low-pass filter is applied to remove ringing artifacts, then artifact removal performance is improved, but image sharpness and edge quality deteriorate
Solution Approach 1:
The patent applies different filtering strengths to different regions of the image based on local characteristics. Edge pixels are identified and given reduced filtering strength to preserve sharpness, while non-edge pixels receive stronger filtering to remove ringing artifacts. This is achieved by calculating edge strength for each pixel and adaptively adjusting the filter coefficient accordingly.
Solution Approach 2:
The filter dynamically adjusts its strength based on local image characteristics rather than applying a fixed filtering operation. The filter coefficient is adaptively determined by analyzing edge strength and artifact presence in each local region, allowing the filter to be strong where needed and gentle where edges exist.
2Manufacturing precision
If conventional two-dimensional filters are used to remove artifacts, then filtering coverage is improved, but computational complexity and processing time increase
Solution Approach 1:
The patent segments the filtering process into distinct stages: edge detection, artifact detection, and selective filtering. By dividing the image processing into these separate steps and applying filtering only where needed rather than uniformly across the entire image, computational complexity is reduced while maintaining effective artifact removal coverage.
3Stability of the object's composition
If filtering is applied to all pixels uniformly, then artifact removal consistency is improved, but edge preservation and natural image quality deteriorate
Solution Approach 1:
Instead of uniform filtering, the patent applies local quality assessment by detecting edges and artifacts in each pixel neighborhood. The filtering operation is then adapted to each local region, maintaining consistency in artifact removal while preserving edges through localized coefficient adjustment.
Data Source
AI summary
An image filtering method, apparatus and system, wherein the method comprising the steps of detecting at least one portion of an edge, wherein the portion of the edge provides an indication that ringing artifact are probable; subjecting at least one portion of a pixel, related to the at least a portion of the edge, to a low pass filter to produce a filtered pixel; and blending the filtered pixel with a value relating to the filter prior to filtering to produce a filtered image.