Exposing forgeries in soccer images using geometric clues
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Exposing forgeries in soccer images using geometric clues Morteza Nasiri 1 & Alireza Behrad 1
Received: 6 October 2017 / Revised: 8 April 2018 / Accepted: 28 May 2018 # Springer Science+Business Media, LLC, part of Springer Nature 2018
Abstract In this study, new algorithms are proposed for exposing forgeries in soccer images. We propose a new and automatic algorithm to extract the soccer field, field side and the lines of field in order to generate an image of real lines for forensic analysis. By comparing the image of real lines and the lines in the input image, the forensic analyzer can easily detect line displacements of the soccer field. To expose forgery in the location of a player, we measure the height of the player using the geometric information in the soccer image and use the inconsistency of the measured height with the true height of the player as a clue for detecting the displacement of the player. In this study, two novel approaches are proposed to measure the height of a player. In the first approach, the intersections of white lines in the soccer field are employed for automatic calibration of the camera. We derive a closed-form solution to calculate different camera parameters. Then the calculated parameters of the camera are used to measure the height of a player using an interactive approach. In the second approach, the geometry of vanishing lines and the dimensions of soccer gate are used to measure a player height. Various experiments using real and synthetic soccer images show the efficiency of the proposed algorithms. Keywords Image forensics . Forgery detection . Automatic camera calibration . Soccer image analysis
1 Introduction Nowadays, the developments in the Internet and digital camera technologies have brought several undeniable advantages like recording memorable scenes, broadcasting news, sharing information and saving events. Today, photo sharing and social Web sites are used by millions
* Alireza Behrad [email protected] Morteza Nasiri [email protected]
1
Electrical Engineering Department, Shahed University, Tehran, Iran
Multimed Tools Appl
of people to share their information and pictures which need secure approaches for authentication and information access [33]. However, the high availability of professional image editing software has made the editing of images easier. This has degraded the general historical reliance on image contents. To counter the problem, several researchers have developed image forensic algorithms to analyze image contents for revealing the traces of image forgery. Several survey studies have discussed different algorithms for image forensics [3, 14, 49, 59]. Existing approaches for tampering detection in digital images can be divided into active and passive approaches. In active approaches, special signature or watermark is embedded in the image to track the traces of tampering [1, 22, 35, 36]. However, these algorithms can be only applied to images generated by expensive and specific cameras. To detect forgery in images acquired by gener
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