Rolling Shutter Ball Imaging Ellipse Separability Filter
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Solution Overview
Problem
Existing imaging devices using CMOS image sensors with rolling shutters face challenges in accurately analyzing the movement of a high-speed moving ball due to image deformation, making it difficult to determine the ball's speed and position accurately.
Innovation Solution
An imaging device that employs a rolling shutter system, captures multiple frame images of the deformed ball, and uses an ellipse separability filter to calculate the center position, major axis, minor axis, and inclination angle of the ball image, allowing for the estimation of the ball's movement parameters such as speed and trajectory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a rolling shutter system is used to capture images in high speed, then the image capturing speed is improved, but the ball image becomes deformed making accurate movement analysis difficult
Solution Approach 1:
The patent applies parameter changes by modifying the filtering approach to match the deformed elliptical shape of the ball image. Instead of using a standard circular filter, an ellipse separability filter is employed with adjustable parameters (ellipse radius, inclination angle) that adapt to the rolling shutter deformation characteristics, enabling accurate ball detection despite the distortion
Solution Approach 2:
The patent utilizes asymmetry by recognizing that the rolling shutter deformation creates an asymmetric elliptical shape in the ball image. The solution incorporates this asymmetric deformation model into the filtering process, where the ellipse parameters (particularly the inclination angle and axis ratio) are optimized to match the actual deformed ball shape, thereby improving detection accuracy under rolling shutter conditions
2Measurement precision
If a mechanical shutter system with flash unit is used to capture multiple ball images, then the ball speed measurement accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent extracts and removes the complex mechanical shutter and flash unit components from the system. Instead of using multiple exposure capture with auxiliary devices, it processes a single frame image captured by the rolling shutter system, extracting only the necessary ball image information through the ellipse separability filter to achieve speed measurement
Solution Approach 2:
The patent replaces the mechanical shutter system with a computational image processing approach. The physical mechanical components (shutter, flash, trigger sensor) are substituted by an algorithmic solution that uses ellipse-based filtering and separability calculations to detect ball position and calculate speed from the deformed image
Data Source
AI summary
An imaging device includes a separability calculating portion for calculating a separability of a frame image by filtering the frame image containing a ball image elliptically deformed using an ellipse separability filter having an inside region and an outside region located outside of the inside region, an estimating portion for estimating a set of a center position, major axis, minor axis and inclination angle of the inside region, the set resulting in a maximum separability by changing the center position, major axis, minor axis and inclination angle of the inside region, as a set of a center position, major axis, minor axis and inclination angle of the ball image, and a speed calculating portion for calculating a speed of the ball based on a difference between the center positions of the ball images estimated by the estimating portion, a number of frames between the frame images and a frame rate.