Color Filter Array Pattern for High-Frequency Sampling
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Solution Overview
Problem
Conventional color imaging elements, particularly those using Bayer arrays, face challenges in reproducing high-frequency images accurately due to color moire and aliasing issues, leading to degraded image quality and resolution.
Innovation Solution
A single plate color imaging element with a novel color filter array pattern that includes filters with varying transmittance properties across different visible light wavelength regions, arranged in a repeating basic array pattern to enhance brightness information sampling and improve color reproduction precision, thereby reducing color moire and aliasing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a Bayer array color filter is used, then the device complexity is reduced and manufacturing is simplified, but color moire and aliasing occur in high-frequency images
Solution Approach 1:
The invention divides the color filter array into multiple distinct patterns (first pattern with G pixels at corners, second pattern with G pixels at center, third pattern with R and B pixels at corners, fourth pattern with R and B pixels at center). This segmentation allows each pattern to capture different spatial frequency information, thereby reducing color moire while maintaining manufacturing simplicity.
2Measurement precision
If an optical low-pass filter is added to reduce color moire, then color reproduction accuracy improves, but resolution degrades
Solution Approach 1:
The invention extracts the anti-aliasing function from the optical low-pass filter and implements it directly in the color filter array pattern design. By carefully arranging pixels with different colors in specific patterns, the system captures high-frequency information without the need for an additional optical low-pass filter, thus avoiding resolution degradation.
3Manufacturing precision
If a random color filter array is used, then color moire is reduced, but demosaicing processing complexity increases
Solution Approach 1:
The invention uses periodic repetition of four distinct patterns in a regular sequence. This periodic structure allows the demosaicing algorithm to predict pixel values based on the known pattern sequence, significantly reducing processing complexity compared to truly random arrangements while still effectively reducing color moire.
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 solution enables high-resolution image data with improved color reproduction precision and optical sensitivity by efficiently sampling brightness information across high-frequency ranges, reducing the need for optical low-pass filters and simplifying demosaicing processing.
Implementation Method 1
a second filter having higher transmittance with respect to a first visible light wavelength region in a visible light wavelength region than other visible light wavelength regions, a third filter having higher transmittance with respect to a second visible light wavelength region which is different from the first visible light wavelength region in the visible light wavelength region than other visible light wavelength regions and a fourth filter having higher transmittance with respect to a third visible light wavelength region which is different from the first visible light wavelength region and the second visible light wavelength region in the visible light wavelength region than other visible light wavelength regions
Implementation Method 2
color filters are disposed on a plurality of pixels comprised of photoelectric conversion elements arranged in a first direction and in a second direction perpendicular to the first direction
Data Source
AI summary
According to a color imaging element and an imaging device of the present invention, because one or more pixels of first filters corresponding to transparence are disposed within a pixel line of each direction of a first direction to a fourth direction of a color filter array, it is possible to acquire brightness information in a high frequency range with high precision and reduce occurrence of a false color (color moire), thereby obtaining image data with excellent resolution. Further, because one or more pixels of the first filters corresponding to transparence are disposed within the pixel line of each direction of the first direction to the fourth direction, it is possible to realize color filters with excellent optical sensitivity.