Stereo Image Parallax Correction for Rolling Shutter Delay
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Solution Overview
Problem
Stereo camera systems with rolling shutters experience erroneous parallax measurements due to lens distortion, leading to incorrect distance estimation, especially when imaging objects with high lateral speeds or during vehicle turns.
Innovation Solution
A stereo image processing device that includes a synchronization unit for synchronizing image capture times, image correction units for parallelizing and correcting images, a parallax measurement unit for detecting parallax, and an object parallax correction unit that corrects parallax errors using delay time data from delay amount holding units, ensuring accurate distance calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a rolling shutter system is used for imaging, then the imaging speed and frame rate are improved, but parallax measurement accuracy deteriorates due to time delay between left and right cameras
Solution Approach 1:
The patent applies preliminary action by calculating and storing delay time information for each pixel before parallax measurement. The system pre-compensates for the rolling shutter time delay by determining the capture time difference for each pixel position and using this information to correct parallax measurements, thereby resolving the contradiction between high-speed imaging and measurement accuracy
Solution Approach 2:
The patent changes the parameter of time synchronization by introducing delay time information that varies for each pixel based on its position. Instead of uniform time alignment, the system adjusts the effective capture time for each pixel according to the rolling shutter scan pattern, transforming the time parameter dynamically to maintain measurement accuracy during high-speed imaging
2Area of stationary object
If lens distortion is present in the camera system, then the field of view and imaging coverage are improved, but parallax measurement accuracy deteriorates due to incorrect line correspondence between left and right images
Solution Approach 1:
The patent applies local quality by making the delay time information specific to each pixel's local position in the image. The delay time varies depending on the pixel coordinates (x, y), allowing the system to account for local distortion effects at different positions in the field of view. This localized approach enables accurate parallax measurement across the entire distorted field of view
Solution Approach 2:
The patent introduces delay time information as an intermediary parameter that mediates between the distorted image coordinates and the true parallax measurement. This intermediary data, stored in delay amount holding units, acts as a correction factor that bridges the gap caused by lens distortion, enabling accurate distance calculation despite the presence of distortion
3Adaptability or versatility
If high lateral speed objects are imaged, then the dynamic range and object detection capability are improved, but parallax accuracy deteriorates due to increased time delay effects
Solution Approach 1:
The patent applies feedback by using the stored delay time information to continuously correct parallax measurements for moving objects. The system feeds back the time delay compensation to the parallax calculation process, adjusting measurements based on the object's motion and the corresponding delay at each pixel position, thereby maintaining accuracy for high-speed objects
Data Source
AI summary
In order to improve parallax accuracy and output an accurate distance, this stereo image processing device is provided with: a stereo image capture unit that captures a plurality of images with different viewpoints; a synchronization unit that synchronizes image capture times when the plurality of images are captured; image correction units that parallelize and output the plurality of images captured by the stereo image capture unit; a parallax measurement unit that detects parallax on the basis of the images outputted by the image correction units; and an object detection unit that detects an object on the basis of the parallax measured by the parallax measurement unit, and is further provided with delay amount holding units that each hold, pixel by pixel, delay times from the image capture times synchronized by the synchronization unit, and an object parallax correction unit that corrects the parallax of the object detected by the object detection unit on the basis of the delay times held by the delay amount holding units.