Color Filter Array for False Color Suppression
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Solution Overview
Problem
Conventional color imaging elements face challenges in suppressing false color and improving high-frequency resolution, particularly in oblique directions, while also simplifying the demosaicing process compared to random arrays.
Innovation Solution
A single-plate color imaging element with a basic array pattern of M×N pixels, where M and N are integers with at least one odd, featuring first filters arranged in a check pattern for high luminance contribution and second filters arranged in horizontal and vertical directions, ensuring a greater proportion of first color pixels for improved demosaicing accuracy and reduced aliasing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Bayer array is used for color filtering, then the imaging element can capture color information, but false color and color moire occur in high-frequency regions
Solution Approach 1:
The imaging element is divided into multiple regions with different color filter arrangements. Specifically, it uses a combination of a Bayer array region and a region with color filters arranged in the same color order as the incident light (e.g., RGB for white light), allowing different handling of different spatial frequencies and directions
Solution Approach 2:
Different regions of the imaging element have different color filter configurations optimized for different purposes. The Bayer region handles general color capture while the specialized region handles high-frequency components, with each region having locally optimized properties for its specific function
2Reliability
If an optical low-pass filter is arranged on the front side of the color imaging element to prevent high frequency wave reduction, then false color is reduced, but resolution is reduced accordingly
Solution Approach 1:
The patent extracts the function of suppressing false color from a single optical low-pass filter and distributes it across multiple regions with different color filter arrangements. This allows selective suppression of false color in specific frequency ranges and directions without uniformly reducing resolution across the entire image
3Reliability
If a three-color random array is used to suppress color moire, then false color is reduced, but the demosaicing process becomes more complex
Solution Approach 1:
The patent uses periodic color filter arrangements (Bayer array with regular patterns) instead of completely random arrangements. This periodicity allows for simpler demosaicing algorithms compared to random arrays, while still effectively suppressing false color through the specific periodic patterns used
4Measurement precision
If green pixels are arranged in a check pattern to improve luminance signal contribution, then luminance accuracy is improved, but color accuracy in oblique directions deteriorates
Solution Approach 1:
The patent introduces asymmetric color filter arrangements in specific regions to compensate for the directional bias introduced by the check pattern. By having different color filter configurations in different regions, it balances the overall color accuracy across all directions while maintaining the luminance benefits of the check pattern
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 effectively suppresses false color and enhances high-frequency resolution, simplifying the demosaicing process and reducing the need for optical low-pass filters, thereby improving image reproduction accuracy and maintaining resolution.
Implementation Method 1
color filters arranged on a plurality of pixels formed by photoelectric conversion elements
Implementation Method 2
pixels formed by photoelectric conversion elements
Data Source
AI summary
A single-plate color imaging element where an array of the color filters includes a basic array pattern of M×N provided with first filters corresponding to a first color with one or more colors and second filters corresponding to a second color with two or more colors with contribution ratios for obtaining luminance signals lower than the first color, the first filters are arranged in a check pattern shape in the basic array pattern, one or more second filters corresponding to each color of the second color are arranged in each line in the horizontal and vertical directions of the array of the color filters in the basic array pattern, and a proportion of the number of pixels of the first color corresponding to the first filters is greater than a proportion of the number of pixels of each color of the second color corresponding to the second filters.