Non-Square Edge Detection Template for Bayer Pattern Noise
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Solution Overview
Problem
Conventional edge detection methods for Bayer pattern color filter arrays often introduce image artifacts like zipper effects, false colors, and blurred edges due to aliasing effects, and are not reliable in noisy or slightly blurred regions, especially during image scaling.
Innovation Solution
An edge detection apparatus with a computing circuit that includes a first multiplier block and an adder unit, performing multiplications on n×m pixels with specific multiplication factors to generate product values, and a determining circuit that assesses these values to determine if a pixel is an edge pixel, using extended detection templates that are not square, allowing for more accurate edge detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional edge detection filters are used for Bayer pattern, then edge direction can be determined, but detection accuracy deteriorates in noisy or slightly blurred regions
Solution Approach 1:
The patent employs non-square detection templates (e.g., 5×3 or 3×5 rectangular kernels) instead of conventional square templates. This asymmetric design better matches the diagonal arrangement of color filters in Bayer pattern, allowing the filter to extend further along edge directions while maintaining appropriate sampling density, thereby improving detection accuracy and reliability in noisy or blurred regions.
Solution Approach 2:
The patent applies different multiplication factors to different pixels within the detection template based on their spatial position and relationship to the center pixel. By assigning weights according to local position (e.g., higher weights for pixels closer to the center, lower weights for peripheral pixels), the filter optimizes edge detection performance for each local region, improving overall detection accuracy while maintaining reliability across varying image conditions.
2Loss of information
If averaging techniques are used for color interpolation, then missing color components can be reconstructed, but image quality deteriorates due to aliasing effects
Solution Approach 1:
The patent performs edge detection using non-square templates before performing color interpolation. By identifying edge locations and directions in advance using the asymmetric template, the subsequent interpolation process can be guided to preserve edges rather than smooth them, preventing aliasing effects and image artifacts while still reconstructing missing color components accurately.
Data Source
AI summary
An edge detection apparatus includes a computing circuit and a determining circuit. The computing circuit includes a first multiplier block and a first adder unit. The first multiplier block includes n×m first multiplier units, wherein each first multiplier unit has a first multiplication factor. The n×m first multiplier units respectively perform multiplications on n×m pixels which are arranged as an n×m matrix to generate n×m first product values based on the corresponding first multiplication factors. The n×m pixels include a target pixel, where n is not equal to m. The first adder unit generates a first computation result according to the n×m first product values. The determining circuit determines if the target pixel is an edge pixel according to at least the first computation result.