Automatic Ball Tracking in Sports Video via Image Difference Analysis
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Solution Overview
Problem
Existing systems for enhancing sports event broadcasts, such as golf and baseball, face challenges in accurately tracking and displaying the ball's path due to technical limitations and the need for manual identification or sensors, which can be costly and disruptive.
Innovation Solution
A fully automatic system that uses a digital processing unit to generate difference images, identify ball candidates based on content alteration thresholds, and apply a ball selection algorithm to track the ball's path without modifying the ball, utilizing co-located cameras and a buffer to ensure accurate and robust tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual identification of the ball is used, then tracking accuracy can be achieved, but time consumption and operational complexity increase
Solution Approach 1:
The system enables automatic ball identification through image processing algorithms that autonomously detect and track the ball without human intervention. The processor automatically analyzes video frames, identifies ball positions, and generates tracking data, making the system self-sufficient in performing the identification task.
Solution Approach 2:
The patent replaces manual mechanical identification with automated electronic image processing. Video capture devices record the scene, and digital processors analyze the images using computer vision algorithms to detect the ball's position and trajectory, substituting human visual inspection with automated computational methods.
2Reliability
If sensors or transducers are installed in the ball, then tracking reliability improves, but the ball's integrity and game authenticity are compromised
Solution Approach 1:
The system introduces an intermediary detection mechanism - video capture devices positioned in the environment that indirectly observe and track the ball without physical contact. This intermediary approach allows reliable tracking while maintaining the ball's physical integrity and the game's authentic conditions.
Solution Approach 2:
Instead of modifying the original ball with sensors, the system creates digital copies or representations of the ball's position and trajectory through video imaging. The visual information captured by cameras serves as a digital replica that enables tracking without altering the physical ball.
3Illumination intensity
If conventional TV exposure settings are used, then the golfer and background are properly exposed, but the ball becomes invisible against the sky
Solution Approach 1:
The system uses video imaging to create a digital copy of the ball's visual appearance and position. By processing the video frames, the system can detect and highlight the ball's position even when it blends with the sky background, effectively creating an enhanced visual representation that overcomes the exposure limitation.
Solution Approach 2:
The patent employs techniques to enhance the ball's visual contrast against the background. By analyzing color and brightness differences in video frames, the system can distinguish the ball from the sky and apply visual enhancements such as coloring or highlighting to make the ball visible without altering the original exposure settings of the scene.
Data Source
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AI summary
The present invention relates to production of a video signal representing a sports scene involving a rapid ball movement in front of an essentially static background. A series of source images (IMG) of the scene is registered. An initial image position (p1) for the moving ball is identified automatically by, for each image (IMG) in said series, producing a difference image between the image (IMG) and an image subsequent thereto. In the difference image, all image elements representing a contents alteration below a threshold level are allocated a first value, and all image elements representing a contents alteration above or equal to the threshold level are allocated a second value. A set of ball candidates is then identified in which each candidate is represented by a group of neighboring image elements that all contain the second value. The group must also fulfil a ball size criterion. The initial image position (p1) is selected from the set of ball candidates based on a ball selection algorithm. Thereafter, the ball is tracked, and a composite image sequence is generated wherein a synthetic trace (?B) representing the path of the moving ball is shown as successively added image data (p1, p2, p3, p4).