Plenoptic Foveated Camera Color Filter Array Design
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Solution Overview
Problem
Conventional light-field imaging devices, such as plenoptic cameras, face challenges in capturing colored light-field data due to reduced light sensitivity and chromatic aberrations caused by Color Filter Arrays (CFAs), which block photons and affect image quality.
Innovation Solution
A CFA design where the color saturation decreases from the centroid to the border of the microimage area, allowing more photons to be captured while minimizing chromatic aberrations, with the CFA covering either the entire or a portion of the sensor microimage, including the centroid, to improve light sensitivity and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Color Filter Array (CFA) is mounted on the sensor to capture colored light-field data, then color information is acquired, but light sensitivity is reduced because photons are blocked by the CFA
Solution Approach 1:
The sensor surface is segmented into multiple regions with different CFA configurations. Some regions have full CFA coverage for color accuracy, while other regions have reduced or no CFA coverage for light sensitivity, allowing both requirements to be satisfied in different parts of the sensor
Solution Approach 2:
Different regions of the sensor are assigned different CFA properties - central regions may have full color filtration for accurate color measurement, while peripheral or specific zones have reduced filtration to capture more photons, creating local optimization for both color accuracy and light sensitivity
2Measurement precision
If a Color Filter Array (CFA) is mounted on the sensor to detect colors, then colored light-field data is captured, but chromatic aberrations occur on the edges of the sensor microimage
Solution Approach 1:
The CFA is configured with varying properties across different regions of the microimage area. Central regions have full CFA coverage for accurate color detection, while edge regions have reduced or modified CFA coverage to minimize chromatic aberrations, allowing color accuracy where most needed while reducing edge artifacts
Solution Approach 2:
The microimage area is divided into zones with different CFA characteristics - a central zone with full color filtration and peripheral zones with reduced filtration, separating the function of color detection from regions prone to chromatic aberrations
3Measurement precision
If a conventional CFA covers the entire sensor microimage to ensure color saturation, then color information is preserved, but light sensitivity is significantly reduced
Solution Approach 1:
Instead of applying CFA coverage to the entire microimage area, the invention applies CFA only to the extent necessary for color information capture. By using partial coverage (e.g., only central regions or specific patterns), the system achieves sufficient color saturation without the excessive photon blocking that would occur with full coverage
Solution Approach 2:
The CFA coverage parameter is changed from binary (full coverage or none) to a gradient or selective coverage model. This allows optimization of the coverage ratio to achieve the minimum necessary color saturation while maximizing photon capture efficiency
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 design enhances light sensitivity by capturing over 84% of photons and reduces chromatic aberrations, resulting in sharper details and colors, especially at the centroid of the sensor microimages, compared to traditional CFAs.
Implementation Method 1
a microlens array positioned in the image focal field of the main lens, and before a sensor on which one microimage per microlens is projected
Implementation Method 2
mount a Color Filter Array (CFA) on top of the sensor
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
A sensor 4 targeted to be mounted on a plenoptic camera 1 comprises at least one microimage area 5 targeted to sense a microimage refracted by a microlens array 3, the microimage area 5 being at least partially covered by a color filter array 6, wherein the color saturation of the color filter array 6 decreases when getting away from a centroid (xi,j, yi,j) of the microimage area 5.