Automotive Camera Focal Timing Around Rolling-Shutter ROI
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Solution Overview
Problem
In automotive cameras operating in rolling shutter mode, focal adjustments during image capture can negatively affect image quality, as they often require time and may occur while the sensor array is exposed, impacting relevant image regions.
Innovation Solution
The method involves identifying a region of interest (ROI) and adjusting focal parameters after the ROI has been captured, using a predefined focal adjustment period that does not interfere with the exposure of the ROI, thereby minimizing quality reductions in critical image areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If focal parameters are adjusted during image capture, then the camera can adapt to different object distances for different functions, but image quality deteriorates due to adjustments occurring during sensor exposure
Solution Approach 1:
The patent segments the sensor array into multiple rows with different exposure timing, allowing focal adjustments to be performed during the exposure period of non-ROI rows without affecting the image quality of ROI rows. This segmentation enables simultaneous focal adaptation and high-quality image capture for different regions.
Solution Approach 2:
The patent performs preliminary identification of the region of interest and calculates the optimal focal adjustment timing before executing the focal parameter changes. This ensures that focal adjustments are scheduled in advance during periods when non-ROI rows are being exposed, preventing quality degradation.
2Adaptability or versatility
If focal parameters are adjusted during image capture, then the camera can switch between different focal settings for various driver assistance functions, but the adjustment process takes time and may occur while the sensor array is exposed
Solution Approach 1:
The patent ensures continuous useful action by performing focal adjustments during the exposure period of non-ROI rows, which would otherwise be capturing lower-priority image data. This utilizes otherwise wasted time for focal adaptation, maintaining continuous operational efficiency without extending total adjustment time.
Solution Approach 2:
The patent implements dynamic focal parameter adjustment based on real-time detection of which rows correspond to the region of interest. The system dynamically schedules focal changes during exposure periods of non-ROI rows, adapting the timing of focal adjustments to the current imaging requirements and maximizing time utilization.
3Manufacturing precision
If all sensor rows are exposed simultaneously (global shutter), then image quality is maintained during focal adjustments, but device complexity and heat dissipation increase
Solution Approach 1:
The patent applies local quality by ensuring high image quality only for the region of interest rows, while allowing focal adjustments during exposure of non-ROI rows. This selective quality approach maintains image quality where needed while simplifying the overall shutter mechanism compared to global shutter requirements.
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 ensures that focal adjustments do not negatively impact the quality of images corresponding to the region of interest, while allowing adjustments to occur without affecting the exposure of other regions, thereby enhancing image quality for driver assistance and computer vision functions.
Implementation Method 1
only photo-electrons that are generated during a defined exposure period, also denoted as integration period, by light hitting the respective sensor pixel contribute to a cumulated charge or cumulated voltage
Data Source
AI summary
A method for focal adjustment of an automotive camera is disclosed. The method includes capturing a first image with an imager of the camera during a first frame period, exposing a plurality of rows of a sensor array of the imager according to a rolling shutter mode, and capturing a second image with the imager during a second frame period after the first frame period. The method further includes determining a first area on the sensor array, which corresponds to a predefined region of interest for the first frame period, determining a first subset of the plurality of rows, determining a focal adjustment period which starts after all rows of the first subset of rows have been exposed during the first frame period, and adjusting at least one focal parameter of the camera during the focal adjustment period according to a predefined focal setting.