|Title:||PRNU-based multi-scale analysis for tampering detection|
|Subject:||Hong Kong Polytechnic University -- Dissertations|
Digital images -- Editing
Image processing -- Digital techniques
Forensic sciences -- Data processing
|Department:||Department of Electronic and Information Engineering|
|Pages:||75 pages : color illustrations|
|Abstract:||An accurate tampering detection is still an open problem in the field of image forensics and locating the subtle tampering area is demanding more research work. In this thesis, we introduce some strategies to solve this problem and investigate the influence of image content on the tampering detection process. Firstly, inspired by the recent research on the multi-scale forgeries detecting strategies, a combination of different tampering probability maps from one image is utilized to build-up a single map so as to strengthen the results with threshold drift and content-dependent neighborhood interaction. Then two new approaches called adaptive window and segmentation guided are studied. The adaptive window method changes the size of detecting window while content inside the detecting window is changing. The segmentation guided method utilizes the central segment correlation in each analysis window to calculate decision statistic more precisely. Extensive experiments have been carried out to study the influence of image content on the result from different tampering strategies. In particular, experiments investigating the effect of image contents including intensity level, size of forgery area and texture complexity have been done. Results show that both the adaptive window and segmentation guided provide better results than state-of-the-art tampering detection methods. The adaptive window method has a lower computational complexity than the segmentation guided approach.|
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