Color Filter Array Layout for Sharper Low-Aliasing Imaging
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Solution Overview
Problem
Existing color filter arrays, such as the Bayer and Quad Bayer patterns, suffer from visible aliasing and reduced sharpness due to their repetitive patterns, which affect color reproduction accuracy and signal-to-noise ratio, especially when capturing small colored objects.
Innovation Solution
A color filter array with an N × M pattern arrangement where 2 × 2 pixel groups are aligned diagonally with primary and non-primary colors, allowing for improved color separation and combination, such as green and yellow or cyan, to enhance sharpness and reduce artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Bayer filter pattern is used, then color information can be captured, but visible aliasing occurs due to the small repetitive pattern
Solution Approach 1:
The patent divides the color filter array into distinct 2x2 pixel groups with unique color configurations (RGGB, GB RG, GRBG, BGRG patterns). Each group is segmented to capture different color combinations, breaking the repetitive single-pattern structure of traditional Bayer filters. This segmentation reduces aliasing while maintaining color capture capability across the entire sensor array.
Solution Approach 2:
The patent introduces asymmetric color distributions within 2x2 pixel groups, where different groups have different color filter arrangements (e.g., RGGB vs. GB RG). This asymmetry breaks the uniform repetitive pattern that causes aliasing, while still allowing demosaic algorithms to reconstruct full-color images through the diverse color sampling across asymmetric groups.
2Quantity of substance
If a Quad Bayer filter pattern is used, then resolution can be improved, but sharpness is reduced and artifacts occur with small colored objects
Solution Approach 1:
The patent applies local quality by giving different 2x2 pixel groups different color filter configurations (RGGB, GB RG, GRBG, BGRG) based on their local position in the array. Each local group has optimized color sampling characteristics for its specific location, improving overall sharpness and reducing artifacts while maintaining high resolution through the combined effect of all locally-optimized groups.
3Ease of manufacture
If primary color filters are arranged in repetitive patterns, then manufacturing is simplified, but color reproduction accuracy deteriorates
Solution Approach 1:
The patent transitions from the traditional single-repeating-Bayer-pattern approach to a multi-dimensional color filter arrangement where 2x2 groups with different color configurations are distributed across the sensor array. This dimensional expansion from 1D repetition to 2D diverse grouping maintains manufacturing feasibility through modular assembly while dramatically improving color reproduction accuracy through diverse color sampling.
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 color filter array improves image sharpness and color accuracy by aligning primary and non-primary colors diagonally within 2 × 2 pixel groups, providing high-quality images in full resolution mode and compatibility with existing Bayer patterns during binning.
Implementation Method 1
a color filter array (CFA), or color filter mosaic (CFM), is a mosaic of tiny color filters placed over the pixel sensors of an image sensor to capture color information. Color filters are needed because the typical photosensors detect light intensity with little or no wavelength specificity, and therefore cannot separate color information.
Implementation Method 2
a color filter array (CFA), or color filter mosaic (CFM), is a mosaic of tiny color filters placed over the pixel sensors of an image sensor to capture color information
Data Source
Figure 1A
Figure 1B
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AI summary
A color filter apparatus includes a two-dimensional array of an N x M pattern of light sensitive elements with a plurality of I x J pixel groups. A 2 x 2 pixel group includes a first color filter of a first color that is a primary color and a second color filter of a second color that consists of green content and one other color. When the first color is green, the second color includes another primary color, but not a third primary color. When the first color is not green, the second color includes the first color.