Face Image Capturing Apparatus with Dual Illuminators for Glare Removal
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Solution Overview
Problem
Conventional face image capturing systems for driver monitoring face difficulties in reliably capturing images due to adverse influences from reflected light from eyeglasses and ambient light, such as sunlight, which affects image processing and detection accuracy.
Innovation Solution
A face image capturing apparatus that employs a camera and dual illuminators, one coaxial and one off-axis, to capture bright pupil, dark pupil, and ambient light face images, with synchronized illumination and image capture timing to remove reflections from eyeglasses and ambient light through luminance calculation and image processing, generating images free of these influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single illuminator is used to illuminate the driver's face, then the face image can be captured, but reflected light from eyeglasses and ambient light interfere with image processing and detection accuracy
Solution Approach 1:
The single illuminator is divided into two separate illuminators: a first illuminator and a second illuminator. These illuminators are positioned at different locations to provide illumination from different directions, allowing the system to capture multiple images with different reflection patterns that can be processed to eliminate glare effects
Solution Approach 2:
Different regions of the imaging system are assigned different functions. The first illuminator provides primary illumination while the second illuminator provides supplementary illumination from a different angle. This local differentiation allows selective elimination of reflections from specific regions (eyeglasses) while preserving useful image information
2Illumination intensity
If ambient light is present during image capture, then the driver's face can be illuminated naturally, but the ambient light creates adverse influence that makes image processing difficult
Solution Approach 1:
The system performs preliminary actions by capturing multiple images under different illumination conditions (with first illuminator only, with second illuminator only, and with both) before the actual image processing stage. This preliminary multi-angle capture creates a set of images with different reflection patterns that can be mathematically processed to eliminate ambient light interference
Solution Approach 2:
The second illuminator acts as an intermediary tool to create a reference image that helps eliminate ambient light effects. By capturing an image with only the second illuminator (which does not cause significant reflection in the eyeglass region), this image serves as a mediator to subtract ambient light contributions from the primary image
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 removes the adverse effects of reflected light from eyeglasses and ambient light, improving the accuracy of face detection and pupil position determination by generating images that are free of these interferences, enhancing the reliability of driver monitoring systems.
Implementation Method 1
the reflected light by buildings, and reflection of the light from the illuminator reflected by eyeglasses of the driver
Implementation Method 2
light including near infrared light is applied from an illuminator to a face of the driver as reference light
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5C
AI summary
A face image capturing apparatus includes a camera (10), an on-axis illuminator (50), an off-axis illuminator (70), an illumination control device (40, 60), an image capturing control device (32), and a luminance calculation process device (22). The camera (10) repeatedly captures an image of a face of an occupant of a vehicle. The illumination control device (40, 60) is configured to adjust an illumination condition of light applied to the face of the occupant. The image capturing control device (32) is configured to control the camera 10 to capture the image of the face at an image capturing timing that is synchronized with a timing for adjusting the illumination condition. The luminance calculation process device (22) is configured to perform a luminance calculation process by using a bright pupil face image (px), a dark pupil face image (py), and an ambient light face image (pz).