Vehicle Camera Scattered Light Removal via Computational Subtraction
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Solution Overview
Problem
Vehicle camera systems face interference from scattered light, which is not effectively addressed by existing mechanical countermeasures like lens hoods, leading to impaired visibility and reduced contrast in images due to undesired background signals and blurring of structures.
Innovation Solution
A computational method using an image signal processor for integrated local contrast intensification and tone mapping to estimate and subtract scattered light intensity, employing a Gaussian distribution approximation function and plausibility checks to stabilize the system, allowing for minimal secondary effects even with partially formed lens hoods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lens hoods are used to suppress interference from reflections, then parasitic images are reduced, but scattered light directly enters the camera causing brightening and contrast loss
Solution Approach 1:
The patent replaces the mechanical lens hood system with a computational image processing system. Instead of using physical structures to block scattered light, the invention uses software-based methods to detect and remove brightening artifacts caused by scattered light, thereby avoiding the mechanical system's limitation of blocking useful light while still eliminating parasitic reflections
Solution Approach 2:
The patent introduces an intermediary processing layer between the camera sensor and the final image output. This intermediary system analyzes image characteristics to identify scattered light patterns and applies corrective transformations, acting as a mediator that separates the harmful scattered light effects from the useful image data without requiring physical light blocking
2Area of stationary object
If aperture angle is increased to 100° to recognise crossing road users, then field of view is improved, but lens hood size increases impairing driver visibility
Solution Approach 1:
The patent eliminates the need for large physical lens hoods by substituting them with computational methods. The image processing system can handle scattered light artifacts even with wide aperture angles, allowing the camera to maintain a 100° field of view for detecting crossing road users without requiring bulky mechanical structures that would block the driver's view
3Illumination intensity
If lens hood size is increased to maintain aperture angle, then scattered light is blocked, but circumferential visibility of driver is impaired
Solution Approach 1:
The patent replaces the mechanical lens hood with a software-based scattered light removal system. This computational approach controls scattered light brightening through image processing algorithms that identify and correct illumination artifacts, thereby maintaining scattered light control without requiring physical structures that would impede the driver's circumferential visibility
Data Source
AI summary
A method removes brightening, which is caused by scattered light, from an image of an external environment of a vehicle captured by a vehicle camera arranged in or on the vehicle. A curve of a total intensity e.g. along a respective line within the image is determined, wherein the total intensity is caused by desired light and scattered light that reach the coverage area of the vehicle camera. An approximation function of a lower limit of the scattered light intensity is estimated. The estimated approximation function is subtracted from the determined curve of the total intensity to produce a modified image with reduced or corrected scattered light.