Title: A new spread spectrum watermarking method using two levels DCT

Authors: Amir Hossein Taherinia, Mansour Jamzad

Addresses: Department of Computer Engineering, Sharif University of Technology, Azadi Avenue, Tehran, Iran. ' Department of Computer Engineering, Sharif University of Technology, Azadi Avenue, Tehran, Iran

Abstract: In this paper, a discrete cosine transform (DCT) based blind watermarking scheme based on spread spectrum communications is proposed. We perform block-based DCT (BDCT) on the host image; then using the DC coefficients of each block, we construct a low-resolution approximation image. We apply BDCT on this approximation image, then watermark is embedded by adding a pseudo random noise sequence into its high frequencies. In detection stage, we extract the approximation image from the watermarked image, then the same pseudo random noise sequence is generated, and its correlation is computed with high frequencies of the watermarked approximation image. In our method, higher robustness is obtained because of embedding the watermark in low frequencies. In addition, higher imperceptibility is gained by scattering the watermark|s bit in different blocks. Compared with related works, our method proved to be highly resistant in cases of many common attacks, while preserving high peak signal to noise ratio for the watermarked images.

Keywords: blind digital watermarking; DCT; discrete cosine transform; spread spectrum watermarking; electronic security.

DOI: 10.1504/IJESDF.2010.032328

International Journal of Electronic Security and Digital Forensics, 2010 Vol.3 No.1, pp.1 - 26

Received: 23 Sep 2008
Accepted: 06 May 2009
Published online: 31 Mar 2010 *

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