Image Stabilization Offset Estimation During Lens Drive
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Solution Overview
Problem
Existing image stabilization systems face accuracy issues when estimating offset values for angular velocity sensors due to errors in drive mechanisms of movable lenses, leading to incorrect motion vectors and reduced shake correction accuracy.
Innovation Solution
An image stabilization apparatus and method that includes a processor or circuit to acquire shake detection outputs, detect motion vectors from captured images, and calculate offset estimates using both observed and a priori offset values, specifically accounting for lens operations during image capturing to correct image blur.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If offset value is estimated using motion vector from angular velocity sensor output, then offset estimation can be performed, but estimation accuracy deteriorates when movable lens is driven due to optical axis shift
Solution Approach 1:
The system dynamically adjusts the offset estimation process based on lens operation state. When a movable lens is driven, the system switches to a different estimation mode that accounts for optical axis shift, thereby maintaining estimation accuracy under varying operational conditions.
Solution Approach 2:
The system changes the estimation parameters and methodology based on whether the lens is stationary or moving. During lens operation, it uses alternative parameters that exclude the optical axis shift component, while in stationary state it uses the standard motion vector-based estimation.
2Measurement precision
If motion vector is calculated from image difference, then camera shake can be detected, but motion components from optical axis shift are superimposed as errors
Solution Approach 1:
The system segments the motion vector calculation into two independent components: one from the angular velocity sensor and another from the image difference. By separating these sources, it can identify and exclude the harmful motion components caused by optical axis shift during lens operation.
Solution Approach 2:
The system introduces an intermediary judgment mechanism that detects lens operation state and mediates between the angular velocity sensor output and image difference results. This intermediary layer filters out the harmful motion components before combining the signals for final shake correction.
3Productivity
If angular velocity sensor output is integrated directly, then shake correction can be performed, but integration errors accumulate due to offset components
Solution Approach 1:
The system implements feedback control by continuously monitoring the lens operation state and adjusting the offset estimation process accordingly. The estimated offset is fed back to correct the angular velocity sensor output before integration, preventing error accumulation while maintaining rapid response to camera shake.
Solution Approach 2:
The system performs preliminary offset estimation and correction before integrating the angular velocity sensor output. By removing the offset component in advance through the estimated value, it prevents integration errors from accumulating while preserving the responsiveness of the shake correction system.
Data Source
AI summary
An image stabilization apparatus includes a first acquisition unit configured to acquire an output of a shake detection device, a motion vector detection unit configured to detect a motion vector, an estimation unit configured to calculate an estimate of an offset value of the shake detection device using an observed offset value and an a priori offset estimate, the observed offset value being obtained using a difference between the output of the shake detection device and the motion vector; and a calculation unit configured to calculate a correction amount for correcting image blur using the output of the shake detection device and the estimate of the offset value, wherein the estimation unit is configured to calculate the estimate of the offset value according to operation for driving a movable lens.