Driver Assistance Visibility Determination Using Contrast Sensitivity Simulation
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Solution Overview
Problem
Existing driver assistance systems using cameras struggle to accurately determine the visibility of objects in a driver's field of view in a manner consistent with human visual perception, often requiring additional sensors and failing to account for the human visual system's sensitivity to contrast frequencies.
Innovation Solution
A method utilizing image processing to simulate the human visual system's contrast sensitivity function by applying a series of Gaussian filters to captured images, allowing the determination of object visibility without additional sensors, by approximating the contrast sensitivity function through differences of Gaussians and weighting these filters to match the human visual system's response to different frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional sensors are used to determine object visibility, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent creates a computational model (contrast sensitivity function) that copies and simulates the human visual system's processing of contrast information. Instead of adding physical sensors to measure visibility, the system uses image processing to replicate how the human eye and brain perceive contrast at different spatial frequencies, thereby determining object visibility using only the existing camera sensor.
2Measurement precision
If the human visual system is taken into account in image processing, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent transforms the image processing approach by changing parameters from standard visual inspection to contrast sensitivity analysis. The system decomposes images into different spatial frequency components and applies the contrast sensitivity function to evaluate visibility at each frequency level. This parameter-based approach systematically incorporates human visual characteristics into the processing algorithm.
Solution Approach 2:
The patent segments the image processing task by dividing it into distinct frequency components. The contrast sensitivity function is applied across multiple spatial frequency bands, allowing the system to evaluate visibility of different object sizes and details separately. This segmentation enables precise visibility determination while maintaining organized and manageable processing complexity.
3Measurement precision
If contrast sensitivity function is simulated using multiple filter differences, then measurement precision is improved, but computational effort increases
Solution Approach 1:
The patent implements a practical approximation of the contrast sensitivity function using a finite number of filter differences rather than attempting to model the complete continuous function. By selecting key frequency components and applying weighted filter differences at these specific frequencies, the system achieves sufficient accuracy for visibility determination while keeping computational requirements manageable for real-time processing.
Data Source
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AI summary
The invention relates to a method for determining the visibility of objects in a field of view of a driver of a vehicle, in which an image is captured by means of a camera and a contrast sensitivity function (16) describing the human visual system is simulated by image processing of the image captured by the camera. The contrast sensitivity function (16) indicates threshold values of a contrast perceptible by the human visual system in dependency of frequencies (52, 60). A particular frequency (52, 60) indicates a number of alternations of light and dark areas per angle unit of the field of view. The contract sensitivity function (16) is approximated by applying a plurality of differences of filters (56) to the image captured by the camera, wherein the differences of filters (56) are each attributed to different frequencies (52, 60) of the contrast sensitivity function (16). A frequency (52) of the contrast sensitivity function (16) corresponding to a maximum of the contrast sensitivity function (16) is determined. A first of the differences of filters (56) is determined depending on the frequency (52) corresponding to the maximum. In dependence on at least said first difference of filters (56) the visibility of an object in the field of view of the driver is determined. The invention further relates to a driver assistance system and a motor vehicle with a driver assistance system.