GEOMETRIC TAMPERING ESTIMATION BY MEANS OF A SIFT-BASED FORENSIC ANALYSIS

GEOMETRIC TAMPERING ESTIMATION BY MEANS OF A SIFT-BASED FORENSIC ANALYSIS Irene Amerini, Lamberto Ballan, Roberto Caldelli , Alberto Del Bimbo and Giuseppe Serra MICC - Media Integration and Communication Center University of Florence, Florence, Italy

Summary ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

The copy-move attack ,[object Object],[object Object],[object Object]

Copy-move & SIFT ,[object Object],[object Object],TARGET : Forensic analysis should provide instruments to detect such a cloning and to estimate which transformation has been performed.

SIFT ,[object Object],[object Object],[object Object],original image L(x,y,σ) D(x,y,σ) Gaussians DoG Gaussian filtering G(x,y,σ) grey-scale I(x,y)

SIFT ,[object Object],[object Object],[object Object],[2] Lowe. “Distinctive image features from scale-invariant keypoints” Int.’l Journal of Computer Vision, 2004

The proposed approach Due to their invariance SIFT features are well-suited to detect forgeries through a matching operation. Suspected image I Features extraction and matching Geometric transformation estimation Hierarchical clustering H

Matching among keypoints ,[object Object],[object Object],[object Object],[object Object]

Hierarchical clustering (1/2) ,[object Object],[object Object],[object Object],[object Object],Criterion: the shortest distance among members belonging to the two different clusters! C 1 C 2 C N-1 C N …… .. C 1,2 C 1,2,8 C 1,2,8, … C N-1,N

Hierarchical clustering (2/2) ,[object Object],[object Object]

Geometric transformation estimation ,[object Object],[object Object],[object Object]

Geometric transformation estimation ,[object Object],Translation parameters are determined by using clusters’ centroids Rotation and scale parameters H

Experimental results: forgery detection

Experimental results: transformation estimation Translation tx tx^ ty ty^ 304 304.02 80.5 81.01 θ θ^ 0 0.040 Rotation (no rotation) sx sx^ sy sy^ 1 1.004 1 0.998 Scaling (no scaling)

Experimental results: transformation estimation tx tx^ ty ty^ 304 305.02 80.5 80.82 Translation θ θ^ 20 20.067 Rotation sx sx^ sy sy^ 1.4 1.404 1.2 1.198 Scaling

Experimental results: transformation estimation

Experimental results: multiple cloning

Conclusions ,[object Object],[object Object],[object Object],[object Object]

GEOMETRIC TAMPERING ESTIMATION BY MEANS OF A SIFT-BASED FORENSIC ANALYSIS

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to GEOMETRIC TAMPERING ESTIMATION BY MEANS OF A SIFT-BASED FORENSIC ANALYSIS

Similar to GEOMETRIC TAMPERING ESTIMATION BY MEANS OF A SIFT-BASED FORENSIC ANALYSIS (20)

Recently uploaded

Recently uploaded (20)

GEOMETRIC TAMPERING ESTIMATION BY MEANS OF A SIFT-BASED FORENSIC ANALYSIS