Image Sensor Exposure Control for Clipped Pixels and Light Flicker
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Solution Overview
Problem
In autonomous driving applications, images captured by image sensors often have high dynamic ranges with clipped pixels and fluctuating intensities due to temporally oscillating light sources, hindering object detection models.
Innovation Solution
A method for adjusting the exposure level of an image sensor by determining an intensity status, selecting an exposure convergence mode, and calculating a new exposure level based on current intensity values and criteria to minimize clipped pixels and intensity fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the exposure level is quickly adjusted to reduce clipped pixels, then the number of clipped pixels decreases, but intensity fluctuations increase
Solution Approach 1:
The system continuously monitors the number of clipped pixels in captured images and uses this feedback to dynamically adjust the exposure level. The exposure control unit compares the actual clipped pixel count against a threshold and modifies the exposure level accordingly, creating a closed-loop control system that balances clipped pixel reduction with intensity stability.
Solution Approach 2:
The exposure level is made dynamic rather than fixed, allowing it to adapt in real-time to changing scene conditions. The system transitions between different exposure levels based on the detected presence and severity of clipped pixels, enabling the imaging system to optimize for both clipped pixel reduction and intensity stability under varying operational conditions.
2Adaptability or versatility
If the exposure level is adjusted rapidly in response to changing brightness, then the adaptability to fast-changing scenes improves, but intensity fluctuations increase
Solution Approach 1:
The system uses feedback from clipped pixel detection to trigger exposure level adjustments only when necessary. By monitoring the actual image quality and detecting clipped pixels, the system responds adaptively to fast-changing scenes while avoiding unnecessary exposure changes that would cause intensity fluctuations in regions without clipping issues.
Solution Approach 2:
The exposure adjustment is driven by local conditions - specifically, the presence of clipped pixels in certain regions of the image. The system adjusts the global exposure level based on local clipping problems detected in the image, allowing adaptive response to fast-changing scenes while maintaining stability in regions where clipping is not an issue.
3Manufacturing precision
If the exposure level is reduced to capture more scene detail, then the number of clipped pixels decreases, but the brightness of the output image decreases
Solution Approach 1:
The exposure level dynamically adapts to balance clipped pixel reduction with maintaining adequate image brightness. Rather than using a fixed low exposure level, the system adjusts the exposure level based on the actual clipping conditions, allowing the output image brightness to be optimized for each scene while still reducing clipped pixels where necessary.
Solution Approach 2:
The system changes the exposure level parameter based on detected clipping conditions. When clipped pixels are detected, the exposure level is reduced to eliminate clipping; when clipping is not present, the exposure level is maintained at higher values to preserve image brightness. This dynamic parameter adjustment resolves the contradiction between clipped pixel reduction and brightness maintenance.
Data Source
AI summary
A method for adjusting an exposure level of an image sensor. The method comprises receiving intensity values of a current image captured by the image sensor, the image sensor having an initial exposure level when the current image is captured. The method comprises determining an intensity status based on comparing at least one characteristic of at least the current intensity values to one or more criteria. The method comprises selecting an exposure convergence mode, from a plurality of exposure convergence modes, based on the intensity status. The method comprises calculating, based on the current intensity values and the exposure convergence mode, a new exposure level for use by the image sensor in capturing a subsequent image.