Color Filter Array Demosaicing for High Color Accuracy
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Solution Overview
Problem
Existing color filter arrays (CFAs) and demosaicing methods in digital cameras face challenges in achieving high-quality image capture and color accuracy.
Innovation Solution
A novel color filter array design featuring a minimal repeating unit with specific filter configurations and a demosaicing method that involves generating multiple resolution images, performing weighted average calculations, and fusing panchromatic images to enhance color accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional color filter array is used, then the device complexity is low, but the color accuracy deteriorates
Solution Approach 1:
The filter array is divided into multiple filter sets (first filter set, second filter set, third filter set) with different spectral characteristics. Each filter set contains specific color filters (red, green, blue) and broadband filters arranged in a quadratic annular pattern, allowing the system to capture multiple spectral components separately and combine them for improved color accuracy.
Solution Approach 2:
The patent combines multiple types of filters with different spectral properties (narrowband color filters and broadband filters) in a composite filter array structure. This composite design enables simultaneous capture of chromatic and panchromatic information, improving color rendering while maintaining a regular repeating pattern for practical implementation.
2Measurement precision
If multiple resolution images are generated and processed, then the color accuracy is improved, but the processing time increases
Solution Approach 1:
The filter array is designed to simultaneously capture multiple spectral components (color and panchromatic information) in a single exposure. This preliminary capture of all necessary data eliminates the need for multiple separate exposures or complex sequential processing, reducing processing time while maintaining high color accuracy.
Solution Approach 2:
The patent merges chromatic information from color filters and panchromatic information from broadband filters into a unified image processing pipeline. By combining these different types of optical information from a single capture, the system achieves high color accuracy without the time penalty of multiple separate processing streams.
3Use of energy by moving object
If a color filter array with broadband filters is used, then the sensitivity is improved, but the color accuracy deteriorates
Solution Approach 1:
The filter array segments the optical information into distinct spectral components using separate filter sets. Broadband filters capture panchromatic information for sensitivity, while dedicated color filters (red, green, blue) capture chromatic information for color accuracy. This segmentation allows each component to be optimized for its specific function.
Solution Approach 2:
Different regions of the filter array have different local qualities - some positions contain broadband filters for high sensitivity/panchromatic capture, while other positions contain narrowband color filters for color accuracy. This local differentiation allows the overall system to achieve both high sensitivity and color accuracy by combining the strengths of each filter type in appropriate locations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution improves color accuracy by 48.7%-55.8% and maintains comparable Peak Signal to Noise Ratio (PSNR) to existing technologies, resulting in high-sensitivity images with improved color fidelity.
Implementation Method 1
The first filter set includes a first color filter having a first spectrum, two second color filters having a second spectrum and a third color filter having a third spectrum. The second filter set includes a fourth color filter having the first spectrum, two fifth color filters having the second spectrum, a sixth color filter having the third spectrum and a plurality of broadband filters.
Implementation Method 2
The color filter array includes at least one minimal repeating unit... for an image sensor
Data Source
AI summary
The present disclosure provides a color filter array. The color filter array includes at least one minimal repeating unit, wherein the at least one minimal repeating unit includes a first filter set and a second filter set. The first filter set includes a first color filter having a first spectrum, two second color filters having a second spectrum and a third color filter having a third spectrum. The second filter set includes a fourth color filter having the first spectrum, two fifth color filters having the second spectrum, a sixth color filter having the third spectrum and a plurality of broadband filters. The second filter set is arranged to form a quadrilateral annulus, and the first filter set is positioned in an interior of the quadrilateral annulus. The present disclosure also provides a demosaicing method for an image captured via the color filter array.