Dual-Sensor Machine Vision Ambient Light Compensation
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Solution Overview
Problem
Machine vision systems and multitouch input systems face challenges in accurately processing images due to the overwhelming effect of ambient light, which can mask objects or produce false positives, especially when ambient light intensity is greater than the illumination source's intensity and varies over time.
Innovation Solution
A system utilizing a pair of synchronized image sensors with a beam splitter to capture images from the same field of view, where one sensor captures light from the illumination source and the other captures adjacent frequencies, allowing for the subtraction of ambient light, thereby reducing signal-to-noise ratio and enhancing image clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If ambient light is present in the environment, then the machine vision system can operate in real-world conditions, but the ambient light overwhelms the image sensor and masks reflections from the illumination source
Solution Approach 1:
The patent divides the light spectrum into different frequency bands using beam splitters and filters. One sensor captures reflections from the illumination source at a specific frequency, while another sensor captures ambient light at adjacent frequencies. This spectral segmentation allows the system to separately measure and subtract ambient light from the total signal, resolving the contradiction between operating in real-world conditions and maintaining detection precision.
Solution Approach 2:
The patent introduces an intermediary measurement approach by using a second sensor to capture ambient light at adjacent frequencies. This intermediary measurement serves as a reference that can be subtracted from the primary measurement, effectively isolating the reflected light signal from the overwhelming ambient light background.
2Illumination intensity
If the intensity of ambient light is significantly greater than the intensity of reflected light, then the system can operate in bright environments, but the ambient light overwhelms the image sensor and masks reflections
Solution Approach 1:
The system segments the total light signal into reflected light component and ambient light component by capturing images at different frequency bands. This segmentation enables the system to tolerate high ambient light intensity while maintaining reliable detection of reflected light through mathematical separation of the components.
Solution Approach 2:
The patent converts the harmful effect of ambient light into a useful measurement by using the ambient light itself as a reference signal. By capturing ambient light at adjacent frequencies and subtracting it from the total signal, the system transforms the overwhelming ambient light from a干扰 factor into a compensatable component, thereby maintaining detection reliability in bright environments.
3Adaptability or versatility
If the amount of ambient light changes over time, then the system can adapt to dynamic environments, but the changing ambient light complicates image processing and reduces accuracy
Solution Approach 1:
The patent employs periodic capture of reference images at adjacent frequencies to track changes in ambient light over time. By continuously updating the ambient light reference through periodic measurements, the system can adapt to dynamic lighting conditions while maintaining processing accuracy through real-time subtraction of the updated reference from the primary images.
Solution Approach 2:
The system uses feedback from the adjacent frequency sensor to continuously monitor and track ambient light changes. This feedback mechanism allows the system to dynamically adjust by subtracting the measured ambient light component from the primary image, thereby maintaining measurement precision even as ambient light conditions change over time.
4Measurement precision
If multiple image sensors and processing capabilities are added to address ambient light, then ambient light compensation is achieved, but the system complexity increases
Solution Approach 1:
The patent segments the imaging function across multiple sensors operating at different frequency bands, with each sensor dedicated to a specific measurement task. This segmentation achieves precise ambient light compensation through spectral separation, while the modular nature of the segmented approach allows for systematic integration and processing.
Solution Approach 2:
The system introduces an intermediary processing stage that subtracts the ambient light reference from the primary image. This intermediary computational step provides effective ambient light compensation, while the use of digital signal processing rather than complex optical hardware keeps the overall system structure manageable.
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 approach effectively compensates for ambient light interference, reducing the impact of moving elements and changing light conditions, and provides a balanced solution between cost, efficiency, and effectiveness for machine vision and multitouch systems.
Implementation Method 1
a beam splitter that splits light to simultaneously send essentially the same field of view (FOV) to the two image sensors
Implementation Method 2
The first of the two image sensors is configured to obtain an image from a frequency range that includes light from the source of illumination and the second of the two image sensors is configured to obtain an image from a frequency range that does not include a material amount of light from the source of illumination
Implementation Method 3
a processor that subtracts the two simultaneously captured images to produce a single image that represents essentially only the light from the source of illumination that was reflected back by the object being imaged
Data Source
AI summary
A system and method utilizing two image sensors to simultaneously capture images of a FOV (field of view). The image sensors are arranged along the same optical path for viewing the FOV. The FOV is illuminated by an illuminator of a specific frequency band. An image is captured by the first image sensor which has a filter that passes at least a portion of the light of the frequency band of the illuminator. An image is captured by the second image sensor that has a filter to pass a band of frequencies adjacent to, but generally not including the frequency band of the illuminator. The images may be manipulated, for example, to provide enhanced performance and/or compensate for variables in the system. A processor subtracts the images to produce an image that represents light reflected back from the illuminator, excluding ambient light at the frequency of the illuminator.