Imaging Device White Balance Compensation via Dual Camera
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Solution Overview
Problem
Inconsistent lighting in outdoor environments poses a challenge for imaging devices, particularly in machine vision systems, as existing compensation methods are approximate and not suitable for real-time applications, leading to errors in image quality.
Innovation Solution
An imaging system comprising a first camera to capture images of a target object and a second camera to determine the color and intensity of the light source, with a processor configured to apply color correction gains to the images from the first camera, enabling real-time adjustment and compensation for varying lighting conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If automatic white balance algorithms are used to compensate for light source color changes, then compensation is provided automatically, but the compensation is only approximate and errors still occur in machine vision outputs
Solution Approach 1:
The system divides the imaging function into two separate cameras: one dedicated to capturing the scene and another dedicated to measuring the light source color. This segmentation allows each camera to be optimized for its specific function, with the second camera providing precise light source measurement without being compromised by scene complexity.
Solution Approach 2:
The second camera acts as an intermediary device that directly measures the light source color and provides this information to the processor. This intermediary measurement system enables accurate color determination that can then be applied to correct the first camera's images, resolving the contradiction between automation and precision.
2Measurement precision
If white cards or white lens covers are used for white balance correction, then accurate color correction can be achieved, but the method is not suitable for outdoor or machine vision use and is only applicable until the light source varies
Solution Approach 1:
The system enables continuous, automatic light source measurement and compensation without requiring external reference objects like white cards. The second camera continuously monitors the light source and provides real-time correction data, making the system adaptable to outdoor environments and machine vision applications where manual intervention is not feasible.
Solution Approach 2:
The system provides continuous light source measurement and compensation rather than periodic or manual corrections. The second camera continuously captures light source information, and the processor continuously applies corrections to the first camera's images, ensuring adaptability to changing lighting conditions in outdoor and machine vision scenarios.
3Measurement precision
If post-processing is used to compensate for light source color, then accurate compensation can be applied to raw pixel data, but this method is not viable in real-time machine vision systems
Solution Approach 1:
The system performs preliminary measurement of the light source color using the second camera before the actual scene capture by the first camera. This preliminary light source characterization allows the processor to apply corrections in real-time during or immediately after image capture, eliminating the need for delayed post-processing and enabling real-time machine vision operation.
Data Source
AI summary
The various embodiments herein relate to imaging devices and systems that capture an image of a target object and separately capture light from the light source illuminating the target object to compensate for inconsistent lighting of that object. Some systems have scene cameras to capture the images of the target objects and a separate light capturing camera to capture the light from the light source. Other embodiments relate to a single camera capturing an image of the target object while simultaneously capturing light from the light source.