Adaptive De-blocking Circuit for Video Signal Detail Preservation
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Solution Overview
Problem
Conventional methods for eliminating block border effects in digital video signals after decoding and decompression often result in loss of image details due to the use of low pass filters.
Innovation Solution
An adaptively de-blocking circuit that adjusts pixels on block borders by referencing neighboring pixels, using a mean calculator to determine a blending factor based on image flatness, which is applied through an α-blending operation to maintain image details and texture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a low pass filter is used to eliminate the block border effect, then the block border effect is reduced, but image details are lost
Solution Approach 1:
The patent applies different filtering strengths to different regions based on local image characteristics. The flatness detection mechanism identifies whether a block border region is smooth or contains edges, and adjusts the filtering intensity accordingly. This allows effective block border removal in flat regions while preserving edges and details in regions with significant pixel variations.
Solution Approach 2:
The patent uses adaptive filtering where the filtering parameters are dynamically adjusted based on local image content. The flatness metric is calculated for each block border region, and the filtering strength is modulated accordingly. This dynamic adaptation allows the filter to be strong where needed (flat regions) and weak where not needed (edge regions), resolving the contradiction between block border removal and detail preservation.
2Object-affected harmful factors
If strong filtering is applied to remove block borders, then the block border effect is eliminated, but image texture is degraded
Solution Approach 1:
The patent makes the filtering operation locally adaptive by detecting flatness characteristics in different regions. In regions with low flatness (containing edges or texture), the filtering is weakened or bypassed to preserve image texture. In regions with high flatness (smooth areas), stronger filtering is applied to remove block borders. This local differentiation resolves the contradiction between border removal and texture preservation.
Solution Approach 2:
The patent changes the filtering parameters (strength, kernel size) based on the detected flatness metric. When flatness indicates a smooth region, stronger filtering parameters are used. When flatness indicates an edge or textured region, weaker parameters are used. This parameter adaptation allows the system to achieve effective block border removal without degrading image texture.
Data Source
AI summary
The present invention discloses an adaptively de-blocking circuit and associated method. A mean is derived according to the neighboring pixels surrounding a central pixel of an image. A blending factor is determined according to a flatness of the image. An updated pixel value of the central pixel is determined by blending the original pixel value of the central pixel and the mean according to the blending factor. Finally, alternatively output the updated pixel value and the original pixel value of the central pixel in response to a block border signal.