Color Filter Array Pattern for High-Frequency Reproduction
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Solution Overview
Problem
Conventional color imaging elements face challenges in suppressing false color and aliasing, particularly in high-frequency areas, and require cumbersome demosaicing processing, with existing random arrays being ineffective for high-frequency sections and Bayer arrays having limitations in oblique direction reproduction accuracy.
Innovation Solution
A single-plate color imaging element with a color filter array featuring a predetermined basic array pattern where the first color filters, contributing most to luminance, are arranged in horizontal, vertical, and oblique directions, and second color filters are added in each line, with a higher proportion of first color filters than second color filters, simplifying demosaicing processing and improving high-frequency reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Bayer array is used for color filtering, then the imaging element can capture color information, but reproduction accuracy of high frequency signals in oblique directions deteriorates
Solution Approach 1:
The color filter array is segmented into multiple types (first type with first color filters in oblique directions, second type with second color filters in horizontal/vertical directions) arranged in a repeating pattern. This segmentation allows different regions to specialize in capturing signals from different directions, resolving the Bayer array's inability to accurately reproduce oblique high frequency signals while maintaining overall color imaging capability.
Solution Approach 2:
Different color filters are assigned to different local regions based on their orientation characteristics. First color filters are placed in regions where oblique direction signals need to be captured, while second color filters are placed where horizontal and vertical signals are prioritized. This local optimization of filter placement improves directional reproduction accuracy without compromising overall color capture.
2Object-affected harmful factors
If an optical low-pass filter is arranged on the front side of the color imaging element, then false color is suppressed, but resolution is reduced
Solution Approach 1:
Instead of using an optical low-pass filter to suppress false color after light reaches the sensor, the patent performs preliminary action by arranging color filters in a specific pattern directly on the pixel array. This pre-arranged filter pattern prevents aliasing and false color generation at the source during light capture, eliminating the need for subsequent optical filtering that would reduce resolution.
Solution Approach 2:
The patent replaces the mechanical/optical low-pass filter system with a color filter array pattern system. Instead of using physical optical filtering to suppress false color, the solution substitutes a carefully designed color filter arrangement that inherently prevents aliasing through its spatial configuration, thereby maintaining resolution while suppressing false color.
3Object-affected harmful factors
If a three-color random array is used, then color moire in low frequency waves is suppressed, but demosaicing processing becomes cumbersome and high frequency false color is not suppressed
Solution Approach 1:
The patent employs periodic action by arranging color filters in a repeating pattern of first and second types. This periodic structure provides regularity that simplifies demosaicing processing compared to random arrays, while the alternating pattern of different color filters effectively suppresses color moire in low frequency waves and prevents high frequency false color through the directional filtering characteristics.
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
This configuration enhances demosaicing accuracy in high-frequency areas, suppresses false color, and increases resolution by optimizing the arrangement of color filters, allowing for simpler processing and reduced aliasing.
Implementation Method 1
a plurality of pixels formed by photoelectric conversion elements arranged in horizontal and vertical directions
Data Source
AI summary
A color imaging element including color filters arranged on pixels, wherein the color filter array includes a basic array pattern including first filters corresponding to a first color that most contributes to obtaining luminance signals and second filters corresponding to two or more second colors other than the first color, the basic array pattern repeatedly arranged in the horizontal and vertical directions, one or more first filters are arranged in each line in horizontal, vertical, and oblique directions of the color filter array, one or more second filters are arranged in each line in the horizontal and vertical directions of the color filter array 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 proportions of the numbers of pixels of each color of the second colors corresponding to the second filters.