This paper presents a chaotic encryption-based blind digital image watermarking technique applicable to both grayscale and color images. Discrete cosine transform (DCT) is used before embedding the watermark in the host image. The host image is divided into $8\times 8$ nonoverlapping blocks prior to DCT application, and the watermark bit is embedded by modifying difference between DCT coefficients of adjacent blocks. Arnold transform is used in addition to chaotic encryption to add double-layer security to the watermark. Three different variants of the proposed algorithm have been tested and analyzed. The simulation results show that the proposed scheme is robust to most of the image processing operations like joint picture expert group compression, sharpening, cropping, and median filtering. To validate the efficiency of the proposed technique, the simulation results are compared with certain state-of-art techniques. The comparison results illustrate that the proposed scheme performs better in terms of robustness, security, and imperceptivity. Given the merits of the proposed scheme, it can be used in applications like e-healthcare and telemedicine to robustly hide electronic health records in medical images.

Secure and Robust Digital Image Watermarking Using Coefficient Differencing and Chaotic Encryption

Dual watermarking framework for privacy protection and content authentication of multimedia

To optimize the tradeoff between imperceptibility and robustness properties, this paper proposes a robust and invisible blind image watermarking scheme based on a new combination of discrete cosine transform (DCT) and singular value decomposition (SVD) in discrete wavelet transform (DWT) domain using least-square curve fitting and logistic chaotic map. Firstly cover image is decomposed into four subbands using DWT and the low frequency subband LL is partitioned into non-overlapping blocks. Then DCT is applied to each block and several particular middle frequency DCT coefficients are extracted to form a modulation matrix, which is used to embed watermark signal by modifying its largest singular values in SVD domain. Optimal embedding strength for a specific cover image is obtained from an estimation based on least-square curve fitting and provides a good compromise between transparency and robustness of watermarking scheme. The security of the watermarking scheme is ensured by logistic chaotic map. Experimental results demonstrate the better effectiveness of the proposed watermarking scheme in the perceptual quality and the ability of resisting to conventional signal processing and geometric attacks, in comparison with the related existing methods.

A novel hybrid of DCT and SVD in DWT domain for robust and invisible blind image watermarking with optimal embedding strength

Robust invisible watermarking plays an important role in copyright protection. Such watermarking has high requirements for robustness and security, and transparency and capacity cannot be ignored. Although there are many algorithms using singular value decomposition, most algorithms do not take security and reliability into account. Moreover, a meaningful watermark cannot be extracted under some attacks, resulting in the failure of copyright protection. In this paper, combined with particle swarm optimization (PSO), a secure and robust dual-embedded watermarking algorithm is proposed. First, the watermark image is encrypted by the generalized Arnold transform, then the original host image and the encrypted watermark image are processed by discrete cosine transform and multi-level discrete wavelet transform, and the singular values of the watermark image are embedded into the low-frequency and high-frequency regions of the host image, respectively. In addition, the embedding factor matrices are optimized by PSO. The simulation results based on the normal and medical host and watermark images show that the algorithm can meet the four basic characteristics of the watermarking algorithm. Moreover, the proposed watermarking algorithm has high capacity and good robustness, and can extract watermark with good visual effect under most attacks, so it can be used in copyright protection.

Dual DCT-DWT-SVD digital watermarking algorithm based on particle swarm optimization

A DWT-SVD based robust digital watermarking for medical image security

This paper presents a new blind and robust image watermarking scheme based on discrete wavelet transform (DWT) and discrete cosine transform (DCT). Two DCT-transformed sub-vectors are used to embed the bits of the watermark sequence in a differential manner. The original sub-vectors are obtained by the sub-sampling of the approximation coefficients of the DWT transform of the host image. During the extraction stage, the simple difference between the corresponding sub-vectors of the watermarked image, gives directly the embedded watermark sequence. Experimental results demonstrate that the proposed technique successfully fulfills the requirement of imperceptibility and provides high robustness against a number of image-processing attacks, such as JPEG compression, noise adding, low-pass filtering, sharpening, and bit-plane removal. Our scheme exhibits also an acceptable to good performance against some geometrical attacks such as resizing and cropping.

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Ali Benoraira

Papers

Blind image watermarking technique based on differential embedding in DWT and DCT domains