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Abstract
In this paper we focus on differential phase shift keying (DPSK) technique to develop a multiple region of interest (ROI) fragile watermarking scheme for image authentication and tampered image recovery. We use a patchwork method to create three areas for ROI image protection. Simultaneously, a pseudo-random number sequence and hamming codec are used to generate a verification key for image authentication checking. On the other hand, set partitioning in hierarchical trees (SPIHT) codec and DPSK technique are used to achieve a multiple region of interest semi-fragile watermarking scheme. Compared with other schemes, our method has three advantages: 1) a SPIHT codec is used to reconstruct the tampered image without any original image, which is different from other schemes using the original image to view the untampered image.; 2) a DPSK technique is used to offer a very secure, low degradation mechanism for secret data embedding; 3) a folding phase distribution DPSK (FPDPSK) technique is developed to improve the DPSK when secret bits are embedded. Compared with the traditional DPSK, the FPSPSK scheme has gained more about a 2 dB PSNR.
Keywords: Discrete Fourier Transform (DFT), Set Partitioning in Hierarchical Trees (SPIHT), Patchwork, Hamming Codec, Tamper, Authentication
1. Introduction
Multimedia is easily reproduced and modified by using image processing software without any trace of manipulation. Obviously, seeing is no longer believing [1]. In general, there are two types of data security schemes: steganography and watermarking. Steganography techniques [2] conceal hidden data so that no one can find it. Based on run-length encoding and modular arithmetic techniques, Chang et al. [3] proposed an effective image steganography scheme to achieve the least possible degradation of the host image. On the other hand, watermarking techniques are usually applied to conceal logo merged in authors' works. There are two kinds of watermarking schemes: robust watermarking and fragile watermarking schemes. In general, a person cannot know whether an image signal is authentic by perceptual inspection. Ideally, the integrity and authenticity of image data can be ascertained by a system without needing external information. Image authentication (IA) is developed for such a goal.
Fragile watermarking schemes have been proposed to authenticate the integrity of images. Techniques by embedding secret data in the spatial domain are more straightforward than the ones...