Vehicle Camera Exposure Switching for Person and License Plate Clarity
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Solution Overview
Problem
Existing exposure control systems for vehicle-mounted cameras fail to capture clear images in low-illuminance environments, leading to issues such as saturation or shadow clipping, especially when the subject is a vehicle or a person.
Innovation Solution
An exposure control device that adjusts exposure conditions based on detected events and illuminance levels, using sensors to differentiate between impacts from persons and vehicles, and adjusts sensitivity accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If exposure control is performed assuming the subject is a person in low-illuminance environments, then the subject can be captured clearly, but the license plate of other vehicles becomes saturated and unreadable
Solution Approach 1:
The exposure control system dynamically adjusts exposure parameters based on detected event types. When a person-related event is detected, the system uses first exposure parameters optimized for low-illuminance human detection. When a vehicle-related event is detected, the system switches to second exposure parameters that prevent license plate saturation. This dynamic switching resolves the contradiction by adapting exposure settings to the specific subject type rather than using a fixed assumption.
Solution Approach 2:
The system changes exposure parameters (such as exposure time, gain, or aperture) based on the detected event type. By detecting whether the event involves a person or a vehicle, the system selects appropriate exposure parameters from different sets, thereby preventing both underexposure of subjects and overexposure/saturation of license plates in low-illuminance conditions.
2Duration of action of stationary object
If the camera operates at low frame rate to save storage space, then recording duration is extended, but impact events may be missed or captured insufficiently
Solution Approach 1:
The system uses periodic shock sensor detection to monitor for impact events during low-frame-rate recording. When impacts exceeding a threshold are detected, the system triggers a temporary switch to high frame rate recording. This periodic monitoring approach allows the system to maintain extended recording duration at low frame rate while ensuring that impact events are reliably detected and captured with sufficient temporal resolution.
Solution Approach 2:
The recording frame rate dynamically switches between low and high based on detected event types. During normal conditions, the system records at low frame rate to extend storage duration. Upon detecting an impact event, the system switches to high frame rate to reliably capture the event details, then returns to low frame rate afterward. This dynamic adjustment resolves the contradiction between recording duration and event detection reliability.
Data Source
AI summary
An exposure control device is configured to control an exposure of a camera mounted to a host vehicle. The exposure control device includes an event information acquisition unit configured to acquire detected information of an event for the host vehicle, and an exposure control unit configured to set an exposure condition based on the detected information acquired by the event information acquisition unit.