Stereo Camera Exposure Timing for Flickering Light Recognition
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Solution Overview
Problem
Conventional in-vehicle camera systems face increased processing load and bus transfer amounts when recognizing flickering light sources, making it difficult to simultaneously recognize multiple objects like preceding vehicles and white lanes without degrading image recognition performance and increasing costs.
Innovation Solution
An in-vehicle image recognition device uses a stereo camera setup with two imaging units that capture images at different timings, synchronizing exposure with the flickering light source's cycle to improve visibility without degrading recognition performance, by adjusting exposure cycles to be Nc times the flickering cycle with a deviation of Ns + 0.5 times the cycle, ensuring consistent brightness capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple imaging units are provided to capture images while deviating exposure timings to recognize flickering light sources, then the visibility of flickering light sources is improved, but the processing load and bus transfer amount are significantly increased
Solution Approach 1:
The patent divides the imaging system into multiple imaging units (first and second imaging units) that operate independently with different exposure timings. Each imaging unit captures images at specific phases of the flickering cycle, allowing the system to recognize flickering light sources without requiring all units to process all images simultaneously, thereby reducing overall processing load.
Solution Approach 2:
The patent utilizes the periodic flickering nature of LED light sources by setting exposure timings at specific phases of the flickering cycle (e.g., 1/4 cycle apart). This periodic sampling strategy allows the system to capture sufficient information about flickering light sources while maintaining a regular, predictable processing rhythm that reduces computational complexity.
2Illumination intensity
If multiple imaging units are provided to capture images while deviating exposure timings to recognize flickering light sources, then the visibility of flickering light sources is improved, but the bus transfer amount is significantly expanded
Solution Approach 1:
The patent segments the image processing tasks across multiple imaging units with different exposure timings. By distributing the capture workload temporally, the system can process images from different units in parallel or at different rates, reducing the peak data transfer volume on the bus compared to a single unit capturing continuously.
Solution Approach 2:
The patent performs preliminary exposure timing adjustment and image capture at optimal phases before recognition processing is needed. By pre-positioning the imaging units at appropriate exposure phases, the system reduces the need for extensive post-capture processing and data transfer, thereby reducing overall bus transfer amounts.
3Measurement precision
If a number of imaging units are provided to capture images while deviating exposure timings, then the flickering light source can be recognized, but the cost is increased
Solution Approach 1:
The patent segments the recognition function across multiple imaging units that can be simpler, lower-cost components rather than requiring a single complex high-performance unit. By distributing the recognition task, the system achieves accurate flickering light source detection using more affordable imaging units with standard specifications.
Solution Approach 2:
The patent designs the imaging units to serve multiple functions: capturing flickering light sources, capturing other road objects (vehicles, pedestrians), and providing depth information through stereo pairing. This multi-functionality reduces the need for specialized expensive hardware, lowering overall system cost while maintaining recognition accuracy.
4Reliability
If the capturing cycle of the camera is close to an integer times the cycle of the flickering light source, then the flickering problem occurs continuously in multiple frames, but increasing the capturing cycle to avoid this increases the time to capture images
Solution Approach 1:
The patent employs periodic sampling at specific phases of the flickering cycle (e.g., 1/4 cycle apart for four imaging units) rather than continuous or integer-multiple sampling. This periodic strategy ensures that each imaging unit captures images at optimally spaced intervals, avoiding the continuous flickering problem while maintaining efficient capture timing.
Solution Approach 2:
The patent pre-calculates and sets the exposure timings of multiple imaging units to specific phases of the flickering cycle before image capture begins. This preliminary timing configuration ensures that images are captured at optimal moments without requiring continuous adjustment or extended capture cycles, thereby avoiding both flickering artifacts and excessive time loss.
Data Source
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AI summary
This vehicle-mounted image recognition device achieves improved performance in flashing light source recognition at low cost and without loss of performance in image recognition applications such as preceding vehicle recognition and white line recognition. At staggered exposure timing, imaging is performed alternately with a first imaging unit (11a) and a second imaging unit (11b), which form a pair in a vehicle-mounted camera. A flashing light source is detected from one or both of the first image (12a) obtained from the first imaging unit (11a) and a second image (12b) obtained from the second imaging unit (11b), and the following times, exposure of the first imaging unit (11a) and the second imaging unit (11b) is matched to when the flashing light source is on. Thereby, flashing light sources are recognized with high accuracy without loss of performance of the image recognition function.