Event-Based Camera Pixel Tuning for Flicker Mitigation
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Solution Overview
Problem
Conventional frame-based cameras incorrectly interpret PWM-modulated brightness signals from flickering light sources, leading to erroneous signal detection and potentially hazardous autonomous decision-making in vehicles.
Innovation Solution
An event-based camera system adjusts pixel parameters, such as exposure time and digital accumulation, to mitigate flickering by altering the imaging behavior of pixels in regions with flickering light sources, reducing the generation of events and improving image reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional frame-based cameras are used to capture PWM-modulated light sources, then the camera can capture images at equidistant time instances, but the camera incorrectly interprets the flickering light signals leading to erroneous detection
Solution Approach 1:
The patent replaces conventional frame-based camera mechanics with event-based camera technology. Instead of capturing images at fixed time intervals, event-based cameras detect changes in light intensity at the pixel level and trigger events only when changes occur. This substitution eliminates the mechanical framing mechanism that causes PWM modulation misinterpretation, enabling accurate detection of modulated light signals while maintaining reliability for autonomous decision-making.
Solution Approach 2:
The patent changes the fundamental parameter of image capture from fixed time intervals to event-driven detection. By adjusting the camera's operating mode from frame-based to event-based, the system can accurately track the temporal characteristics of PWM-modulated light sources. This parameter change allows the system to distinguish between different modulation frequencies and patterns, resolving the detection accuracy issue while maintaining safety for autonomous vehicles.
2Measurement precision
If event-based camera with adjusted pixel parameters is used, then flickering artifacts are reduced and signal detection accuracy is improved, but the device complexity increases due to parameter adjustment mechanisms
Solution Approach 1:
The patent applies segmentation by dividing the pixel array into multiple regions with different pixel parameters. Instead of uniformly adjusting all pixels, the system identifies regions containing flickering light sources and applies specialized parameter settings only to those regions. This segmentation approach reduces the overall complexity by avoiding unnecessary parameter adjustments in non-flickering regions while maintaining high detection accuracy in affected areas.
Solution Approach 2:
The patent implements local quality by assigning different pixel parameters to different spatial regions based on their content. Regions with flickering light sources receive parameters optimized for flicker detection, while other regions use standard parameters. This localized approach allows the system to achieve high measurement precision for flicker detection without uniformly increasing device complexity across the entire camera system.
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 method effectively reduces flickering artifacts, enhancing the accuracy of image processing and decision-making in autonomous vehicles by minimizing erroneous signal detection from PWM-controlled light sources.
Implementation Method 1
each pixel typically comprises a photodetector (e.g., a photodiode) converting light to, e.g., charge
Data Source
AI summary
The invention relates to a method for mitigating flickering lights in a scene of interest imaged by an event-based camera, wherein the event-based camera comprises a plurality of pixels, wherein an imaging behaviour of the plurality of pixels is influenced by a set of pixel parameters comprising at least one exposure time parameter and/or at least one digital accumulation parameter, and wherein the method comprises the following steps: 1) operating the event-based camera having an assignment of first values to the set of pixel parameters, said operating providing a plurality of events generated by the event-based camera; 2) reconstructing an image based on at least the generated plurality of events, 3) determining at least one region in the reconstructed image, said determined at least one region corresponding to at least one spatial region in the scene of interest comprising at least one flickering light source active during the operating of the event-based camera, 4) determining a subset of pixel parameters of the set of pixel parameters, which subset of pixel parameters influences imaging behaviour of pixels in the determined at least one region, assigning second values for the determined subset of pixel parameters, which second values are determined to mitigate flicker in the pixels of the determined at least one region, and updating the first values assigned to the subset of pixel parameters with the second values, and 5) further operating the event-based camera with the updated set of pixel parameters. The invention also relates to an assembly and to a vehicle comprising said assembly.