Log-Polar Based Scheme for Revealing Duplicated Regions in Digital Images

Author

Wu, Qiumin ; Wang, Shuozhong ; Zhang, Xinpeng

Author_Institution

Sch. of Commun. & Inf. Eng., Shanghai Univ., Shanghai, China

Volume

18

Issue

10

fYear

2011

Firstpage

559

Lastpage

562

Abstract

Region duplication is a common type of digital image tampering. This paper presents a log-polar based approach to detect such forgery even if the copied area has been rotated and/or scaled. We compute log-polar fast Fourier transform (LPFFT) on image blocks to approximate the log-polar Fourier transform (LPFT). LPFFT is based on a nearly log-polar system where conversion to log-polar coordinates only involves 1-D Fourier transform and interpolation operations. In addition to rotation and scaling invariance, computation complexity of LPFFT is O(n²logn) , much lower than O(n⁴) of LPFT when n is large. Similarity of the LPFFT results between different blocks provides indication of image tampering. Experimental results show efficacy of the proposed method.

Keywords

copy protection; fast Fourier transforms; image processing; interpolation; security of data; 1D Fourier transform; LPFFT; digital image tampering; image blocks; interpolation operations; log-polar coordinates; log-polar fast Fourier transform; region duplication; scaling invariance; Complexity theory; Discrete Fourier transforms; Fast Fourier transforms; Interpolation; Materials; Image forensics; pseudo log-polar transform; regional duplication detection; rotation and scaling invariance;

fLanguage

English

Journal_Title

Signal Processing Letters, IEEE

Publisher

ieee

ISSN

1070-9908

Type

jour

DOI

10.1109/LSP.2011.2163507

Filename

5971766