Vehicle Camera Image Correction Brightness Control
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Solution Overview
Problem
Current vehicle camera systems suffer from image quality degradation in boundary regions due to light fall-off caused by wide-angle lenses, leading to increased noise and reduced brightness, especially in low light conditions, where existing image correction methods are not reliably activated or deactivated based on scene brightness and temperature.
Innovation Solution
A method where a camera system's control unit activates and deactivates an image correction function based on the current brightness level and temperature of the scene, using a gain factor and exposure time as operating parameters to adjust modes between normal and low light modes, ensuring reduced noise and improved image quality in boundary regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If an image correction function is activated to compensate for light fall-off in boundary regions, then brightness uniformity is improved, but noise in boundary regions increases due to digital amplification
Solution Approach 1:
The image correction function is dynamically activated or deactivated based on scene brightness conditions. In normal light mode, the correction function is activated to improve brightness uniformity. In low light mode, it is deactivated to prevent noise amplification. This dynamic switching resolves the contradiction by adapting the correction application to lighting conditions.
Solution Approach 2:
The system changes the operating parameters (gain factor, exposure time) based on brightness conditions. In low light mode, a higher gain factor and longer exposure time are used, and the image correction function is deactivated. In normal light mode, lower gain factor and exposure time are used with the correction function activated, thus managing the noise-brightness tradeoff through parameter adjustment.
2Area of stationary object
If a wide-angle optic device is used to capture environmental regions, then field of view is improved, but light transmission in boundary regions decreases causing vignetting
Solution Approach 1:
The image correction function applies different brightness compensation to different regions of the image. Boundary region pixels are multiplied by a compensation factor greater than 1 to compensate for the lower light transmission caused by the wide-angle lens, thus achieving local brightness uniformity while maintaining the wide field of view.
3Illumination intensity
If gain factor is increased to improve signal amplification in low light mode, then brightness is improved, but noise amplification increases
Solution Approach 1:
The system dynamically adjusts the gain factor based on brightness conditions. In low light mode, a higher gain factor is applied to improve brightness, accepting the associated noise amplification. In normal light mode, a lower gain factor is used to minimize noise. The image correction function is selectively activated/deactivated to manage the overall noise-brightness balance.
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
This approach effectively reduces noise in boundary regions, enhances automatic white balance, and prevents false brightness interpretations caused by dark current, resulting in improved image structure and reliability across varying lighting conditions.
Implementation Method 1
images of an environmental region of the motor vehicle are captured by means of an image sensor of the camera system via an optic device of the camera system
Implementation Method 2
the optic device has a lower transmission factor for light incident at a greater angle of incidence. This optical effect results in the fact that the pixels in the boundary region of the image are darker than in the center of the image. This effect is referred to as 'boundary light fall-off' and resembles the so-called vignetting
Implementation Method 3
In the low light mode, a greater gain factor with respect to the normal light mode is adjusted, with which the analog image signals of the image sensor are amplified
Implementation Method 4
In the low light mode, the exposure time is additionally increased and the frame rate of the image sensor is reduced
Data Source
Figure 1
Figure 2~4
AI summary
The invention relates to a method for operating a camera system of a motor vehicle, wherein images of an environmental region of the motor vehicle are captured by means of an image sensor (15) of the camera system via an optic device (16) and an image correction function is activated by means of a control unit (17) of the camera system, in which a light fall-off in a boundary region of the images caused by the optic device (16) is compensated for, wherein a current brightness level of the environmental region is captured by means of the control unit (17) and the activation and deactivation of the image correction function are effected depending on the current brightness level.