Green Pixel Disparity Correction in Image Sensors
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Solution Overview
Problem
Existing image sensors face challenges in correcting green disparity due to differences in neighboring pixel arrangements and electrical cross-talk, leading to unsymmetrical distortion in captured images.
Innovation Solution
A method and circuit for normalizing pixel values in a Bayer array by averaging and combining values of adjacent pixels, with limited pixel values adjusted to preserve edge sharpness, using a non-linear limiting function to correct pixel values of green pixels in different arrangements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If standard Bayer filter array is used with diagonal green pixels, then color image capture is achieved, but green pixel disparity and unsymmetrical distortion occur due to different neighboring pixel arrangements
Solution Approach 1:
The patent applies local quality by implementing different normalization procedures for Gr and Gb green pixels based on their specific neighboring pixel arrangements. Gr pixels (in blue rows) and Gb pixels (in red rows) are processed differently to account for their distinct electrical cross-talk environments, thereby achieving uniform green pixel output despite structural asymmetry in the Bayer filter array.
2Manufacturing precision
If green pixel values are normalized using simple averaging of neighboring pixels, then green disparity is reduced, but edge sharpness is lost due to oversmoothing
Solution Approach 1:
The patent implements dynamic normalization by adaptively adjusting the normalization factor based on local image characteristics. The system calculates the standard deviation of neighboring pixel values and uses this to dynamically determine the degree of smoothing applied, thereby preserving edges while normalizing green pixel disparities in homogeneous regions.
Solution Approach 2:
The patent changes the normalization parameter (normalization factor) based on the local variance of pixel values. In regions with low variance (smooth areas), a higher normalization factor is applied to correct green disparity, while in regions with high variance (edge areas), a lower factor is used to preserve edge sharpness, thus adaptively balancing distortion correction and detail preservation.
Data Source
AI summary
A method of displaying a captured image includes using an array of pixels to capture an image. The array of pixels includes a first plurality of pixels of a first color, a second plurality of pixels of a second color, and a third plurality of pixels of a third color. The pixels are arranged into rows and columns and the pixels of the third plurality of pixels have two different arrangements within the array of pixels with respect to neighboring pixels. The method includes, for each pixel in the third plurality of pixels, normalizing the pixel's value as a function of the pixel values of at least six other pixels in the third plurality of pixels. The method also includes displaying the captured image using a normalized value for the pixel value of each pixel in the third plurality of pixels.