Vehicle Face Detection Illumination Uniformity
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Solution Overview
Problem
Existing face detection systems using near-infrared cameras face accuracy issues due to non-uniform luminance caused by shadows from external light sources, such as sunshades, which can affect the detection of feature points like the iris, leading to decreased accuracy.
Innovation Solution
A detection system with a light source section comprising multiple near-infrared LEDs that emit light to different portions of the face, an imaging section to capture face images, and a control unit that divides the face image into areas, calculates average pixel values, and adjusts the light intensity based on reference and measurement values to maintain uniform luminance, thereby reducing the impact of shadows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If near-infrared light is emitted toward an entire face of a driver, then the face image can be captured, but non-uniform luminance is generated due to shadows from sunshades or external illumination
Solution Approach 1:
The face image area is divided into multiple divided image areas corresponding to each light emitting device. The control unit calculates average pixel values for each divided image area and adjusts the light amount of each light emitting device independently based on the difference between reference and measurement values, thereby compensating for non-uniform luminance caused by shadows
Solution Approach 2:
Instead of using a single light source for the entire face, the patent employs multiple light emitting devices that can be independently controlled. Each light emitting device is assigned to a specific divided image area, allowing localized adjustment of light intensity to compensate for shadow effects in different regions of the face
2Illumination intensity
If multiple light emitting devices are used to illuminate different portions of the face, then luminance uniformity can be improved, but the system complexity increases
Solution Approach 1:
The face image area is divided into multiple divided image areas corresponding to each light emitting device. The control unit calculates average pixel values for each divided image area and adjusts the light amount of each light emitting device independently based on the difference between reference and measurement values, thereby compensating for non-uniform luminance caused by shadows
Solution Approach 2:
The system uses the captured face image itself to determine the appropriate light amount for each light emitting device. The control unit calculates average pixel values from the image, compares them with reference values, and automatically adjusts the light output without requiring external intervention or complex manual calibration
3Measurement precision
If the light amount of light emitting devices is adjusted based on average pixel values, then detection accuracy of feature points can be maintained, but processing time increases
Solution Approach 1:
The face image area is divided into multiple divided image areas corresponding to each light emitting device. The control unit calculates average pixel values for each divided image area and adjusts the light amount of each light emitting device independently based on the difference between reference and measurement values, thereby compensating for non-uniform luminance caused by shadows
Solution Approach 2:
Instead of processing the entire face image at full resolution, the patent calculates average pixel values only for specific divided image areas corresponding to regions with shadow effects. This partial processing approach maintains detection accuracy for critical feature points while reducing overall processing time
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 system effectively suppresses the decrease in accuracy of feature point detection by adjusting light levels, ensuring consistent illumination and improving the reliability of eye iris detection even under varying environmental conditions.
Implementation Method 1
a light source section including a plurality of light emitting devices, each of the plurality of light emitting devices being configured to emit near infrared light toward a different portion of a face of an occupant
Implementation Method 2
an imaging section configured to capture a face image with reflected light of the near-infrared light emitted to the face of the occupant
Data Source
AI summary
A detection system includes a light source section that includes a plurality of light emitting devices, each of the plurality of light emitting devices emitting near-infrared light toward a different portion of a face of an occupant of a vehicle, an imaging section that captures a face image with reflected light of the near-infrared light emitted to the face of the occupant, and a control unit that extracts feature points and a face image area of the face of the occupant from the face image captured by the imaging section. Based on a plurality of divided image areas obtained by dividing the face image area according to the plurality of light emitting devices, respectively, the control unit individually dims light from the light emitting devices corresponding to the respective divided image areas.