Camera Module Coordinate Transformation for Shake and Distortion
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Solution Overview
Problem
Existing camera shake and lens distortion correction methods are inadequate in accuracy, particularly under low illuminance and with rolling shutter CMOS image sensors, as they fail to account for focal plane phenomena and motion differences within the image surface.
Innovation Solution
A camera module with an image pickup portion, motion detecting portion, and coordinate transformation processing portion that synchronizes image data with motion sensor output to correct camera shake and lens distortion by transforming image coordinates based on detected motion, using correction coefficients for optical system distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If image processing is executed to correct camera shake by obtaining motion amount from image, then camera shake correction is achieved, but calculation processing becomes complicated and measurement accuracy under low illuminance is reduced
Solution Approach 1:
The patent replaces image-based motion detection with a motion sensor (gyro sensor or acceleration sensor) to detect camera shake. This substitution of the detection mechanism eliminates the need for complex image processing calculations while providing accurate motion amount measurement, directly resolving the contradiction between measurement accuracy and calculation complexity.
2Measurement precision
If the whole image position is moved in conjunction with motion amount, then camera shake correction is achieved, but it becomes difficult to cope with difference in motion amount due to position within image surface
Solution Approach 1:
The patent applies different correction amounts to different regions of the image based on their position relative to the optical center. The correction amount is calculated as a function of the distance from the optical center, allowing the system to adaptively handle motion differences across the image surface while maintaining overall correction accuracy.
3Productivity
If rolling shutter CMOS image sensor is used, then image capture is achieved, but focal plane phenomenon causes difference in movement amount within one picture
Solution Approach 1:
The patent performs preliminary correction of the focal plane phenomenon by calculating and applying position-dependent correction amounts before final image output. By addressing the movement amount difference caused by rolling shutter exposure timing in advance, the system maintains both capture efficiency and measurement precision.
4Measurement precision
If lens distortion correction is applied, then optical system distortion is corrected, but additional processing steps are required
Solution Approach 1:
The patent merges lens distortion correction with camera shake correction into a unified processing framework. Both corrections are applied through coordinate transformation using the same motion amount data from the motion sensor, eliminating the need for separate processing steps while maintaining correction accuracy.
Data Source
AI summary
A camera module includes an image pickup portion, a motion detector, and a coordinate transformation processor. The motion detector detects a motion of the image pickup portion while an image of a subject is captured in the image pickup portion. The coordinate transformation processor executes coordinate transformation processing for collectively transforming coordinates of the image captured by the image pickup portion in such a way that effects on the image caused by camera shake of the image pickup portion, and by a distortion of an optical system used to obtain the image, are suppressed based on the motion of the image pickup portion detected by the motion detector, and based on a correction coefficient with which the distortion of the optical system is corrected. Technology used for the camera module may be applied to a CMOS image sensor.