Gray Image Watermarking Research Articles

Color image watermarking using spatio-chromatic complex Hadamard transform in sequency domain

PurposeWatermarking technique is one of the significant methods in which carrier signal hides digital information in the form of watermark to prevent the authenticity of the stakeholders by manipulating different coefficients as watermark in time and frequency domain to sustain trade-off in performance parameters. One challenging component among others is to maintain the robustness, to limit perceptibility with embedding information. Transform domain is more popular to achieve the required results in color image watermarking. Variants of complex Hadamard transform (CHT) have been applied for gray image watermarking, and it has been proved that it has better performance than other orthogonal transforms. This paper is aimed at analyzing the performance of spatio-chromatic complex Hadamard transform (Sp-CHT) that is proposed as an application of color image watermarking in sequency domain (SD).Design/methodology/approachIn this paper, color image watermarking technique is designed and implemented in SD using spatio-chromatic – conjugate symmetric sequency – ordered CHT. The color of a pixel is represented as complex number a*+jb*, where a* and b* are chromatic components of International Commission on Illumination (CIE) La*b* color space. The embedded watermark is almost transparent to human eye although robust against common signal processing attacks.FindingsBased on the results, bit error rate (BER) and peak signal to noise ratio are measured and discussed in comparison of CIE La*b* and hue, saturation and value color model with spatio-chromatic discrete Fourier transform (Sp-DFT), and results are also analyzed with other discrete orthogonal transforms. It is observed from BER that Sp-CHT has 8%–12% better performance than Sp-DFT. Structural similarity index has been measured at different watermark strength and it is observed that presented transform performs better than other transforms.Originality/valueThis work presents the details and comparative analysis of two orthogonal transforms as color image watermarking application using MATLAB software. A finding from this study demonstrates that the Complex Hadamard transform is the competent candidate that can be replaced with DFT in many signal processing applications.

Invariant color image watermarking approach using quaternion radial harmonic Fourier moments

Moments and moment invariants have become a powerful tool in gray image watermarking. More recently, a few moment-based approaches were developed to embed watermark into color host image by marking the luminance component or three color channels, and they always cannot obtain better imperceptibility and robustness because of ignoring the correlation between different color channels. Quaternion is a generalization of the complex numbers, and can treat a color image as a vector field without losing color information. In this paper, based on algebra of quaternions and radial harmonic Fourier moments (RHFMs), we introduced quaternion radial harmonic Fourier moments (QRHFMs) for color images, which can be seen as the generalization of RHFMs for gray-level images. We analyzed and discussed the geometric invariant property of QRHFMs, and proposed a geometric invariant color image watermarking scheme using QRHFMs. Experimental results show that the proposed watermarking scheme not only provides better imperceptibility and robustness against various attacks (including common image processing operations and geometric distortions), but also yields better watermark detection performance than some state-of-the-art image watermarking schemes.

Digital Image Watermarking Algorithms Based on Dual Transform Domain and Self-Recovery

Abstract In view of dual watermarking algorithm for dual two value image watermarking, the watermark information there is a gray image watermarking in the expression is obviously insufficient. The proposed embedded in the carrier image on the dual watermark includes a two watermark image and a gray image watermarking algorithm, the persuasive power while maintaining the original two values of the watermark robustness at the same time, improve the watermark information. In order to balance the robustness and invisibility of watermarking algorithm, this paper analyzes the embedding position and strategy of transform domain algorithms, the DC coefficient in the carrier image is divided into blocks of DCT spectrum and spectrum on the combination of DWT coefficient method and the advantage of embedded dual watermarking, and use the NEC characteristic of the algorithm is improved adaptive based on the embedded mode. The gray image watermark bit plane decomposition compression high four bit plane information as watermarking, in reducing the original watermark loading and enhance the overall strength of self recovery system. This paper from the working principle, classification of digital watermarking, attack types, performance index, evaluation method and uses six aspects were introduced to the digital watermarking technology. Simulation study of a digital image watermarking algorithm based on DCT transform and Arnold transform, the algorithm’s imperceptibility, robustness and security are analyzed, the algorithm for embedding process.

Three-Dimensional Mesh Model Watermarking Algorithm

Watermark information is embedded in three-dimensional mesh model through three-dimensional watermarking algorithm for effective copyright protection. The widely use of three-dimensional grid model attracts more attention on the copyright protection. The digital watermark algorithm with the NURBS model based on the wavelet transform aims to get the virtual grayscale images using the control point coordinate. Then we can embed the watermark into the virtual gray image watermark. It can change the three-dimensional models into two-dimensional images. And this algorithm can enhance the operability and simplicity of the watermark embedding. Experiments show that the proposed algorithm is easy to implement, simple in principle, and the extracted watermark is clearly visible, moreover, the model does not need to be directly modified, so it has good robustness. Watermarked model does not change in the visual, it has good invisibility.

A Novel Gray Image Watermarking Scheme

An effective and integrated image watermarking scheme mainly includes watermark generation, watermark embedding, watermark identification, and watermark attack. In this paper, a novel discrete wavelet transform domain image watermark scheme is proposed to meet the watermarking properties: security, imperceptibility and robustness. Here watermark comes from a meaningful binary image encrypted by two-dimensional chaotic stream encryption, which has more security. In the procedure of watermark embedding, the watermark is embedded into host image through selecting and modifying the wavelet coefficients using genetic algorithms with a simple fitness function to improve the imperceptibility of watermarked image. In order to identify the owner of extracted watermark, synergetic neural networks are used in the watermarking identification to overcome the limitation of correlation analysis or the human sense organ after some attacks. The results of our scheme realization and robust experiments show that this scheme has preferable performance.