WYMgW Color Filter Array for Low-Light Machine Vision
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Solution Overview
Problem
Machine vision systems, particularly in autonomous vehicles, face challenges in nighttime driving due to low light levels, where existing color filter arrays like Bayer filters are inefficient, leading to poor light sensitivity and signal-to-noise ratios, making it difficult to distinguish essential road features.
Innovation Solution
A color filter array configuration with two white filter portions and one each of yellow and magenta filter portions, arranged diagonally, known as the WYMgW filter, which allows a majority of light to pass through, significantly improving light sensitivity and signal-to-noise ratio, enabling better low-light operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Bayer filter array is used in the camera, then color information can be captured, but light sensitivity and signal-to-noise ratio deteriorate in low light conditions
Solution Approach 1:
The patent applies local quality by using different filter types (white, yellow, magenta) in different spatial locations within the filter array. Specifically, white filters are placed at corners to maximize light transmission, yellow filters are positioned to enhance sensitivity to yellow traffic lights, and magenta filters are used to improve red light detection. This spatial variation in filter properties optimizes both color information capture and light sensitivity in different regions of the image sensor.
Solution Approach 2:
The patent employs composite materials by combining multiple types of optical filters (white, yellow, magenta) in a single filter array structure. This composite approach allows the system to simultaneously achieve color discrimination and enhanced light sensitivity, as each filter type contributes different spectral transmission characteristics that collectively improve low-light performance while maintaining color information capture capability.
2Measurement precision
If traditional color filters are used to capture color information, then color discrimination is achieved, but light transmission is blocked significantly reducing light sensitivity
Solution Approach 1:
The patent applies color changes by strategically selecting and positioning filters with different spectral transmission characteristics. White filters transmit all visible wavelengths to maximize light throughput, yellow filters selectively transmit yellow wavelengths for traffic light detection, and magenta filters transmit red and blue wavelengths. This color-specific filtering approach enables the system to maintain color discrimination while optimizing light transmission efficiency for specific traffic-related color detection.
3Measurement precision
If filters are used to improve color detection, then color information is enhanced, but overall light sensitivity decreases
Solution Approach 1:
The patent applies segmentation by dividing the image sensor into multiple regions, each covered by different filter types. The filter array is segmented into white filter regions for general light capture, yellow filter regions for yellow traffic light detection, and magenta filter regions for red light detection. This spatial segmentation allows each region to be optimized for its specific function, improving both color information detection and light sensitivity without requiring filters across the entire sensor.
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 WYMgW filter array enhances light sensitivity by 3 to 5 times compared to Bayer filters, improving the ability to identify road features like traffic lights, signs, and markings at night without compromising daytime performance, thus enabling reliable nighttime autonomous vehicle navigation.
Implementation Method 1
a color filter array having a plurality of sections. In some embodiments, each section can include a first white filter portion, a yellow filter portion, and a magenta filter portion
Implementation Method 2
The WYMgW filter array enhances light sensitivity by 3 to 5 times compared to Bayer filters, improving the ability to identify road features
Data Source
AI summary
A machine vision system having a first camera configured to be coupled to a vehicle. The camera includes an optical stack having a color filter array with a plurality of sections. Each section includes a first white filter portion, a yellow filter portion, a magenta filter portion, and a second white filter portion.