Large-Zoom Lens Calibration for Accurate Image Stabilization
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Solution Overview
Problem
Conventional image stabilization techniques fail to provide accurate results at high optical zoom ratios, especially between 10× to 40×, and require manual calibration of each lens, which is time-consuming.
Innovation Solution
A system utilizing an inertial measurement unit (IMU) and digital signal processing at a frame-accurate level, combined with a lens projection model, to automate the calibration process for large zoom ratios, incorporating extra compensation based on movement information and calibration values determined through a simulation framework.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If digital image stabilization is used for large optical zoom lenses, then the system can provide image stabilization, but the stabilization accuracy deteriorates as optical zoom ratio increases
Solution Approach 1:
The patent changes the fundamental parameters of the stabilization system by introducing IMU sensor data and lens projection models alongside traditional DIS algorithms. This parameter enhancement enables the system to maintain accuracy at high optical zoom ratios (10× to 40×) where conventional DIS alone fails, as the combined approach can distinguish between external vibration and object movement more effectively.
Solution Approach 2:
The patent uses an intermediary calibration process that bridges the gap between the lens optical characteristics and the stabilization algorithm. By calibrating the lens projection function and using calibration targets, the system creates an intermediary model that improves the accuracy of movement compensation at high zoom levels.
2Measurement precision
If manual calibration is performed for each lens, then accurate calibration can be achieved, but the process becomes time-consuming
Solution Approach 1:
The patent implements self-service calibration where the system automatically captures images of calibration targets, processes them through the lens projection model, and determines calibration parameters without requiring manual intervention. This automated calibration process maintains high measurement precision while significantly reducing the time required compared to manual technician calibration.
Solution Approach 2:
The patent performs preliminary calibration actions by capturing images of calibration targets at multiple positions and zoom levels before actual usage. This preliminary calibration data is then used to generate the lens projection function and calibration parameters, enabling accurate stabilization without requiring time-consuming manual calibration during operation.
3Device complexity
If conventional DIS is used without IMU, then the system structure remains simple, but the capability to distinguish between external vibration and object movement is lost
Solution Approach 1:
The patent merges multiple data sources including IMU sensor measurements, lens projection models, and captured images into a unified stabilization system. This combination enables the system to reliably distinguish between external vibration and object movement by cross-referencing motion data from multiple sources, significantly improving reliability while accepting increased system complexity.
Data Source
AI summary
An apparatus comprising an interface and a processor. The interface may be configured to receive pixel data of an environment and movement information about the apparatus. The processor may be configured to process pixel data arranged as video frames, measure movement information, generate a replay record in response to the video frames of calibration targets captured during a vibration pattern applied to the apparatus and the movement information of the vibration pattern, implement an image stabilization compensation in response to a lens projection function and the movement information, perform an extra compensation in response to calibration values and perform calibration operations to determine the calibration values. The replay record may comprise the video frames generated at a plurality of pre-defined zoom levels of a lens and the calibration operations may comprise determining coordinates of the calibration targets for each of the video frames in the replay record.