Dynamic Rearview Mirror Glare Reduction via Multi-Exposure Image Processing
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Solution Overview
Problem
Existing in-vehicle vision systems struggle to effectively reduce glare from both direct and reflected illumination sources, such as headlights and road reflections, as current solutions like polarization and tinting either fail to address vertical glare or compromise image quality.
Innovation Solution
A method involving the generation of high dynamic range images using short-exposure and long-exposure images, where pixel ratios and differences are used to identify glare regions, which are then modified with short-exposure image data to reduce glare, while preserving optimal image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If polarization is applied to reduce glare from reflected illumination, then glare reduction is achieved in one plane, but glare from other orientations (e.g., vertical buildings) is not reduced
Solution Approach 1:
The patent segments the glare reduction problem by capturing multiple images with different polarization orientations (e.g., horizontal and vertical). Each image captures glare from specific orientations, and the system processes these segmented views separately before combining them into a composite image that reduces glare from all orientations.
Solution Approach 2:
The patent adds the dimension of polarization orientation by capturing images at multiple polarization angles. Instead of relying on a single polarization plane, the system captures images across multiple polarization dimensions, allowing it to address glare from various orientations including both horizontal reflections and vertical structures.
2Object-affected harmful factors
If tinting is applied to the lens to reduce glare, then glare is reduced, but color information and image sensitivity are reduced
Solution Approach 1:
The patent uses polarizing filters as intermediaries that selectively block glare based on polarization orientation without uniformly reducing light intensity. These filters act as mediators that allow desired light (non-glare) to pass through while blocking harmful glare, thereby reducing glare without significantly compromising color information or image sensitivity.
Solution Approach 2:
The patent applies different polarization orientations to different regions or aspects of the image capture process. By using multiple polarized images with different orientations, the system selectively reduces glare in specific orientations while preserving color information and sensitivity in other regions, rather than applying uniform tinting across the entire image.
3Object-affected harmful factors
If short-exposure images are used to reduce glare, then glare is reduced, but image brightness and detail in dark regions are insufficient
Solution Approach 1:
The patent merges multiple polarized images with different exposure characteristics into a single composite image. By combining images captured with different polarization orientations and exposure settings, the system achieves both glare reduction (from short-exposure polarized images) and adequate brightness/detail (from long-exposure polarized images) in the final output.
Solution Approach 2:
The patent changes exposure time as a variable parameter across different polarized image captures. By capturing images with varying exposure times at different polarization orientations, the system can select and combine the optimal portions of each image to achieve both glare reduction and sufficient brightness in the final composite image.
4Illumination intensity
If long-exposure images are used to capture dark regions, then image brightness is improved, but glare from light sources becomes excessive
Solution Approach 1:
The patent segments the image capture process by using different polarization orientations for different exposure times. Long-exposure images are captured with polarization orientations that minimize glare from specific directions, while short-exposure images handle regions with intense light sources. This segmentation allows the system to achieve adequate brightness without excessive glare in the final composite 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
This approach effectively reduces glare in all regions, enhancing image quality by combining short- and long-exposure image data, thereby addressing the limitations of existing glare reduction methods.
Implementation Method 1
an array of pixels, each including a photodetector
Implementation Method 2
polarization may be applied to a lens and/or cover glass of the camera device
Data Source
AI summary
A method for generating a glare-reduced image from images captured by a camera device of a subject vehicle includes obtaining a short-exposure image and a long-exposure image and generating a resulting high dynamic range image based on the short-exposure and long-exposure images. Pixel values are monitored within both the short- and long-exposure images. A light source region is identified within both the short- and long-exposure images based on the monitored pixel values. A glaring region is identified based on the identified light source region and one of calculated pixel ratios and calculated pixel differences between the monitored pixel values of the long- and short-exposure images. The identified glaring region upon the resulting high dynamic range image is modified with the identified light source region within the short-exposure image. The glare-reduced image is generated based on the modified identified glaring region upon the resulting HDR image.