Multi-Sensor Exposure Timing Synchronization for Rolling Shutter Asynchrony
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Solution Overview
Problem
Cameras with rolling shutters and multiple image sensors often capture images with exposure timing asynchrony, leading to errors in stereoscopic depth mapping, image merging, and other operations, even when images are captured contemporaneously.
Innovation Solution
An imaging system synchronizes exposure timings between multiple image sensors by adjusting the exposure timing of one sensor to align with another, ensuring that the start or end of the exposure period of one sensor matches that of another, thereby reducing or eliminating asynchrony.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If rolling shutter is used to capture images, then the entire image sensor can be exposed gradually row by row, but the bottom of the image depicts the scene at a later point in time than the top, causing temporal asynchrony
Solution Approach 1:
The system performs preliminary timing analysis to identify the exposure timing difference between first and second image sensors before capturing images. Based on this preliminary analysis, the system adjusts the exposure timing of one sensor relative to the other in advance, ensuring that corresponding regions (such as regions of interest) are exposed at the same moment in time, thereby eliminating temporal asynchrony caused by rolling shutter effects
2Productivity
If two cameras capture images contemporaneously with different exposure timings, then both images can be captured at the same time, but differences in exposure timing cause the same region to be depicted at different points in time, leading to errors in stereoscopic depth mapping and image merging
Solution Approach 1:
The system implements a feedback mechanism where the exposure timing of the second image sensor is adjusted based on the exposure timing of the first image sensor. The system analyzes the timing relationship between the two sensors and dynamically adjusts the second sensor's exposure timing to ensure that corresponding regions are exposed at the same moment, thereby maintaining high spatial-temporal alignment accuracy while enabling contemporaneous image capture
Solution Approach 2:
The system changes the exposure timing parameter of one image sensor relative to the other to eliminate temporal asynchrony. By adjusting the exposure timing parameter based on the identified timing difference between sensors, the system ensures that corresponding regions (including regions of interest) are depicted at the same point in time across both images, resolving the contradiction between contemporaneous capture and alignment accuracy
Data Source
AI summary
Examples are described of automatic exposure timing synchronization. An imaging system includes a first image sensor configured to capture a first image according to a first exposure timing, including by exposing first region of interest (ROI) image data at the first image sensor for a first ROI exposure time period. Based on the first exposure timing, the imaging system sets a second exposure timing for a second image sensor to capture a second image. Capture of the second image according to the second exposure timing includes exposure of second ROI image data at the second image sensor for a second ROI exposure time period. The second exposure timing may be set so that the start of the second ROI exposure time period aligns with the start of the first ROI exposure time period, and/or so that the first and second ROI exposure time periods overlap.