Embedding Stage Research Articles

Digital Watermarking in Color Image Based On Joint Between DCT and DWT

The massive distribution and development in the digital images field with friendly software, that leads to produce unauthorized use. Therefore the digital watermarking as image authentication has been developed for those issues. In this paper, we presented a method depending on the embedding stage and extraction stag. Our development is made by combining Discrete Wavelet Transform (DWT) with Discrete Cosine Transform (DCT) depending on the fact that combined the two transforms will reduce the drawbacks that appears during the recovered watermark or the watermarked image quality of each other, that results in effective rounding method, this is achieved by changing the wavelets coefficients of selected DWT sub bands (HL or HH), followed by applying DCT transform on the selected sub band's coefficients, this method focuses on the invisibility for the embedded watermark bits, and the quality for the watermarked image; furthermore it focuses on a subjective for the recovered watermark after extraction stage. The proposed method was evaluated by using simple image quality matrix illustrated in the results, and it was found that the proposed method provide good objective quality, the recovered watermark extracted successfully and the quality of recovered watermark are survived.

More secure lossless visible watermarking by DCT

This study proposes a scheme for using modified coefficients of the DCT of an image to generate a lossless visible watermark. The major contribution of the proposed technique is the improved security against attack to remove watermarks under stricter assumption of Kerckhoffs' principle. After the host images and watermarks are decomposed into several frequencies, the DCT coefficients of the watermark are embedded into the DCT coefficients of the host image. Integer mapping is then used to perform 2-dimensional DCT. The major advantage of the method is the improved security achieved by using a random permutation matrix to factorize the transformation matrix. That is, since the embedding stage multiplies the transformation matrix by a random permutation matrix, illicit users, even under the stricter assumption of Kerckhoffs principle that the proposed embedding method is known by illicit users, cannot properly recover the host image without the correct permutation matrix. Unlike methods that embed the watermark in quantized frequency-domain coefficients, the watermarked image remains in raw lossless image form instead of some lossy form of quantized coefficients e.g., JPEG-formatted. Maintaining the lossless format of the watermarked image provides reversibility.

An improved watermarking algorithm using variable block image features

The ease in digital imaging has led to a decrease in image fidelity where illegal reproduction of multimedia information has become difficult to detect. The most challenging problem is to protect image copyright against illegal copies. Therefore a watermark detection process is required to verify the owner of the image. This paper proposes a blind algorithm to extract the watermark. This algorithm is robust against noise and geometric attacks for grayscale images. Robust feature points are detected using the Harris Detector. In the embedding stage, sequences are placed into regions located around feature points. The sequences used are PN, Gold and decimal. In the extraction process, image features are re-allocated using the same detector. Each feature point is used as a center of an N × N region. This region is moved horizontally and vertically within its neighboring pixels. Each move should be registered in a matrix as a correlation value of this region with the initial sequence. This procedure is repeated for all feature points till we find all the watermarked regions. The maximum correlation obtained will determine the center of the watermarked region. The proposed algorithm is robust against a wide variety of tests and is compared to other schemes.

CLSM: COUPLE LAYERED SECURITY MODEL A HIGH-CAPACITY DATA HIDING SCHEME USING WITH STEGANOGRAPHY

Cryptography and steganography are the two significant techniques used in secrecy of communications and in safe message transfer. In this study CLSM – Couple Layered Security Model is suggested which has a hybrid structure enhancing information security using features of cryptography and steganography. In CLSM system; the information which has been initially cryptographically encrypted is steganographically embedded in an image at the next step. The information is encrypted by means of a Text Keyword consisting of maximum 16 digits determined by the user in cryptography method. Similarly, the encrypted information is processed, during the embedding stage, using a 16 digit pin (I-PIN) which is determined again by the user. The carrier images utilized in the study have been determined as 24 bit/pixel colour. Utilization of images in .jpeg, .tiff, .pnp format has also been provided. The performance of the CLSM method has been evaluated according to the objective quality measurement criteria of PSNR-dB (Peak Signal-to-Noise Ratio) and SSIM (Structural Similarity Index). In the study, 12 different sized information between 1000 and 609,129 bits were embedded into images. Between 34.14 and 65.8 dB PSNR values and between 0.989 and 0.999 SSIM values were obtained. CLSM showed better results compared to Pixel Value Differencing (PVD) method, Simulated Annealing (SA) Algorithm and Mix column transform based on irreducible polynomial mathematics methods.

Localized & self adaptive audio watermarking algorithm in the wavelet domain

This paper presents an adaptive audio watermarking algorithm in the wavelet domain to optimize the payload under the perceptual transparency constraints of audio signal by strategically using some of its local features. Unlike existing algorithms, the watermark payload in this approach is made adaptive based on the nature of the audio signal. This localized feature based approach to determine the payload addresses the issue of over-loading and under-loading the audio signals with watermark data making the payload optimized for each individual audio host signal. Some audio features are strategically extracted and the most discriminatory features are selected using Principal Component analysis (PCA) approach. A mathematical model is designed using selected audio features like energy, zero cross mean and short time energy to evaluate the degree of embedding under perceptual transparency. It is used to estimate the number of watermarking bits to be inserted for a particular audio signal which makes the approach adaptive in nature optimizing the watermarking payload. At the embedding stage, watermark is embedded in the host audio signal in the third level detailed coefficient of wavelet domain which strikes a balance between the contradicting design parameters of perceptual transparency, robustness and optimized payload. Watermark extraction in this paper is blind with good robustness to signal processing attacks. Experimental results validate that the proposed adaptive algorithm provide good imperceptibility with good robustness against signal processing attacks at adjustable payload for different types of audio signals. Comparative analysis indicates that this proposed adaptive algorithm has better performance in terms of imperceptibility and robustness in comparison to uniform watermarking algorithm.

Particle Swarm Optimization and Discrete Wavelet Transform based Robust Image Watermarking

Objectives: Watermarking technique on digital images with improved robustness and with optimum results can be achieved by using the intelligent technique Particle Swarm Optimization (PSO). Discrete Wavelet Transform (DWT) is used to uncover perceptually significant coefficients from the digital image. Methods: PSO is one amongst the efficient techniques in optimizing a problem having many numbers of candidates. This robust technique consists of two stages namely embedding and extraction stages. Insertion of watermark into the image is done at the embedding stage. Before embedding watermark into the image perform DWT and select any one of the bands LL, LH, HL and HH. Initially select the coefficients randomly and the optimal DWT coefficients for embedding the watermark at various positions are identified by PSO. Findings: In watermark extraction stage, the embedded watermark is identified by doing the reverse process. Robustness of the digital image watermarks implies the strength of the watermark against various image processing attacks and this can be checked by evaluating Cross Correlation value that is Normalized (NCC) and for fidelity Peak Signal to Noise Ratio (PSNR). It is evident that the robustness of the image is well maintained by this technique. As a further improvement any of the other intelligent technique namely Ant Colony Optimization can be used for optimization evaluation. Applications: Digital image watermarking plays a vital role in copyright infringement issues and it helps in predicting the authorized user by the digital signature that is watermarked in the image.

Robust watermarking in non-ROI of medical images based on DCT-DWT.

Increasing demand and utilization of telemedicine require transmission of medical information and images over internet. Since authenticity of received images is crucial and patient's information should be included with minimum changes in images, robust watermarking schemes are needed. In this paper, we propose a robust watermark method that embeds patient's information outside the region of interest (ROI) in medical image. In order to find appropriate regions for embedding, we use saliency as a means of measuring importance of regions and find blocks having minimum overlap with the ROI. The algorithm employs wavelet transform and also discrete cosine transform (DCT) domains in the embedding stage and redundantly embeds watermark to increase robustness against possible alterations. Moreover, voting is utilized in the extraction phase. Experimental results show the efficiency of the proposed method and better results are obtained as compared to comparable methods with same size of the watermarked data.

How do coral barnacles start their life in their hosts?

Coral-associated invertebrates are the most significant contributors to the diversity of reef ecosystems, but no studies have examined how larvae manage to settle and grow in their coral hosts. Video recordings were used to document this process in the coral barnacle Darwiniella angularis associated with the coral Cyphastrea chalcidicum Settlement and metamorphosis in feeding juveniles lasted 8-11 days and comprised six phases. The settling cyprid starts by poking its antennules into the tissue of the prospective host (I: probing stage). The coral releases digestive filaments for defence, but tolerating such attack the cyprid penetrates further (II: battling stage). Ecdysis is completed 2 days after settlement (III: carapace detachment). The barnacle becomes embedded deep in the coral tissue while completing metamorphosis between 4 and 6 days (IV: embedding stage), but reappears as a feeding juvenile 8-11 days after settlement (V: emerging stage; VI: feeding stage). Cyprids preferably settle in areas between the coral polyps, where they have a much higher survival rate than on the polyp surfaces.

Wavelet Packet and Hybrid Filter Based Digital Watermarking

In this paper, a new watermark algorithm that based on wavelet packet transform and hybrid filter is proposed for watermark of digital images, which include many high frequency components. The proposed watermark algorithm is used in the high frequency component of image and applies watermark to the overall subband that include the lowest frequency band. And the watermark is embedded on input image and hybrid filtering concept has been adopted to remove the noise that was added to the original image in watermark embedding stage. The quality of the watermarked image has been analyzed with PSNR. From the simulation results, the proposed algorithm shows better invisibility and robustness performance compare with conventional watermark methods. Especially, it demonstrates better robustness for high image compression in the remote sensing images application.

Organizational Promoting Factors for SME BCP (2)

In Oct. 2013, one hundred small and medium enterprises (SMEs) were surveyed regarding their business continuity. 70% of the SMEs surveyed had implemented BCP. Our previous paper, “Organizational Promoting Factors for SME BCP,” reviewed the survey results using correlation and path analysis. The review found directives from the president to be the most influential factor of BCP implementation and that there were two different levels of BCP implementation and BCP embedding. Over 60% of the companies that had implemented BCP had had difficulties embedding BCP. Our previous paper identified the BCP environment and its four key component factors, including organizational BCP momentum and company-wide information sharing that would affect BCP embedding, among others. It also identified four key BCP advantages related to normal operations, including enhancing marketing advantage and building employee togetherness, which had a causal relationship with successful cases of BCP embedding. This paper reviews our previous survey results in detail to find key factors separately in tasks and problems as well as in corporate culture groups. It also re-identifies four factors in the tasks and problems group as well as three factors in the corporate culture group. This paper also analyzes the relationships among the perceived BCP advantages to determine if some of them affect the remaining advantages. It finds that organizational strategic risk/BCP mind and employees’ risk mind bring about other BCP advantages, which could be interpreted to mean that two minds , one top-down and one bottom-up, are critical in the BCP embedding stage.

DWT-Based Watermarking Using 2DLDA for Color Images

In this paper, we propose a watermarking algorithm based on Discrete Wavelet Transform (DWT) by using Two-dimensional Linear Discriminant Analysis (2DLDA) for color images. At first, the color image is converted into the YIQ color space and then transformed into the frequency domain by DWT. During the embedding stage, two watermarks of reference and logo are embedded into the quadrature chrominance component. Then, watermark extraction is done by 2DLDA from the quadrature chrominance component based on DWT. By embedding the reference watermark and using 2DLDA, the training covariance matrix can be directly computed from 2D image samples and the robustness of watermark extraction can be ensured. Also, the computation complexity can be reduced. By considering the Human Visual System (HVS), experimental results have shown that the watermark can be correctly extracted and better robustness is provided after various image attacks.

Patchwork-Based Audio Watermarking Method Robust to De-synchronization Attacks

This paper presents a patchwork-based audio watermarking method to resist de-synchronization attacks such as pitch-scaling, time-scaling, and jitter attacks. At the embedding stage, the watermarks are embedded into the host audio signal in the discrete cosine transform (DCT) domain. Then, a set of synchronization bits are implanted into the watermarked signal in the logarithmic DCT (LDCT) domain. At the decoding stage, we analyze the received audio signal in the LDCT domain to find the scaling factor imposed by an attack. Then, we modify the received signal to remove the scaling effect, together with the embedded synchronization bits. After that, watermarks are extracted from the modified signal. Simulation results show that at the embedding rate of 10 bps, the proposed method achieves 98.9% detection rate on average under the considered de-synchronization attacks. At the embedding rate of 16 bps, it can still obtain 94.7% detection rate on average. So, the proposed method is much more robust to de-synchronization attacks than other patchwork watermarking methods. Compared with the audio watermarking methods designed for tackling de-synchronization attacks, our method has much higher embedding capacity.

Ultrastructural evaluation of shrinkage artefacts induced by fixatives and embedding resins on osteocyte processes and pericellular space dimensions.

The integrity of the interface between the osteocyte (Ot) process and the canalicular wall was investigated in terms of change in the lateral dimensions of the Ot process in relation to the canalicular width, i.e., widening of the pericellular space. This has been interpreted as shrinkage of the Ot process relative to the canalicular wall during sample preparation stages of fixation, dehydration, and resin embedding. Sprague-Dawley rat tibial cross-sections were prepared for transmission electron microscopy (TEM). Four different fixative preparations: paraformaldehyde (PF), modified Karnovsky's (MK), glutaraldehyde (GRR) with ruthenium red (GRR), and zinc formalin (ZF); and two different embedding resins: LR Gold (LRG) and Epon812 (Epon) were evaluated. It was found that for LRG embedding, formalin-only fixatives (PF and ZF) induced lower shrinkage than GRR-containing fixatives (MK and GRR). In contrast, for Epon embedding, MK showed the highest shrinkage, while no differences were found between the remaining fixatives (PF, ZF, and GRR). All formalin-containing fixatives (MK, PF, and ZF) induced similar shrinkage in both embedding media. The most dramatic difference was for GRR fixation, which in combination with LRG embedding showed ∼ 62% more shrinkage than with Epon embedding, suggesting that the combination of GRR fixation and LRG embedding synergistically amplifies Ot shrinkage. These differences likely suggest a role of the resin in secondarily influencing the tissue structure following fixation. Further, the work confirms LRG as a poor embedding medium for bone specimens, as it causes large variations in shrinkage depending on fixation.

Full 4-D quaternion discrete Fourier transform based watermarking for color images

Among the few existing color watermarking schemes, some use quaternion discrete Fourier transform (QDFT). By modulating at least one component of QDFT coefficients, they spread the watermark over two or three of the RGB color channels. However, these schemes do not fully utilize the four-dimensional (4-D) QDFT frequency domain and some also suffer from a watermark energy loss directly at the embedding stage. In this paper, we first establish the links that exist between the DFT of the three RGB color channels and the components of QDFT coefficients while considering a general unit pure quaternion. Then, for different unit pure quaternions i, j, k or their linear combinations, we discuss the symmetry constraints one should follow when modifying QDFT coefficients in order to overcome the previous drawbacks. We also provide a general watermarking framework to illustrate the overall performance gain in terms of imperceptibility, capacity and robustness we can achieve compared to other QDFT based algorithms, i.e. when fully considering the 4-D QDFT domain. From this framework we derive three schemes, depending on whether i, j or k is used. Provided theoretical analysis and experimental results show that these algorithms offer better performance in terms of capacity and robustness to most common attacks, including JPEG compression, noise, cropping and filtering and so on, than other QDFT based algorithms for the same watermarked image quality.

Reprint of: Peer methods with improved embedded sensitivities for parameter-dependent ODEs

Recently, an extension of peer two-step methods to parameter-dependent IVPs has been proposed by the author and E. Kostina where additional embedded stages allow cheap computation of solution derivatives (sensitivities) with respect to problem parameters. For each parameter only one additional ‘satellite’ stage was used which provides a high-order approximation to a neighboring solution. However, the accuracy of the sensitivities was only first order in the time stepsize h. In the present paper we derive implicit peer methods where the sensitivity accuracy is of second order with the same number of stages. Approximate implementations yield efficient linearly-implicit methods for stiff problems and explicit predictor–corrector-type versions for nonstiff problems. Tests confirm improved and more robust convergence of inexact Newton iterations in shooting for different applications with nonstiff and stiff IVPs.

Peer methods with improved embedded sensitivities for parameter-dependent ODEs

Recently, an extension of peer two-step methods to parameter-dependent IVPs has been proposed by the author and E. Kostina where additional embedded stages allow cheap computation of solution derivatives (sensitivities) with respect to problem parameters. For each parameter only one additional ‘satellite’ stage was used which provides a high-order approximation to a neighboring solution. However, the accuracy of the sensitivities was only first order in the time stepsize h. In the present paper we derive implicit peer methods where the sensitivity accuracy is of second order with the same number of stages. Approximate implementations yield efficient linearly-implicit methods for stiff problems and explicit predictor–corrector-type versions for nonstiff problems. Tests confirm improved and more robust convergence of inexact Newton iterations in shooting for different applications with nonstiff and stiff IVPs.

A highly robust two-stage Contourlet-based digital image watermarking method

In this paper we propose a blind and highly robust watermarking method consisting of two embedding stages. In the first stage, the odd description of image is divided into non-overlapped fixed size blocks and the signature (watermark) is embedded in the high frequency component of the Contourlet transform (CT) of the blocks. In the second stage, the signature is embedded in the low frequency component of the global CT of the image. The main issue associated with two-stage blind watermarking is the selection of the less affected signature among the two embedded signatures. In this paper a measure is introduced to decide between the two extracted signatures. Simulation results indicate that the proposed method achieves higher robustness compared to other known watermarking methods. Moreover, since watermark is embedded in the local as well as global CT coefficients of two different frequency bands, the proposed method is robust against a wide range of attacks. This is due to the fact that most of the attacks affect either a specific frequency band or a specific location in the watermarked image.

Optimized 3D Watermarking for Minimal Surface Distortion

This paper proposes a new approach to 3D watermarking by ensuring the optimal preservation of mesh surfaces. A new 3D surface preservation function metric is defined consisting of the distance of a vertex displaced by watermarking to the original surface, to the watermarked object surface as well as the actual vertex displacement. The proposed method is statistical, blind, and robust. Minimal surface distortion according to the proposed function metric is enforced during the statistical watermark embedding stage using Levenberg-Marquardt optimization method. A study of the watermark code crypto-security is provided for the proposed methodology. According to the experimental results, the proposed methodology has high robustness against the common mesh attacks while preserving the original object surface during watermarking.

A reversible data hiding method by histogram shifting in high quality medical images

Enormous demands for recognizing complicated anatomical structures in medical images have been demanded on high quality of medical image such as each pixel expressed by 16-bit depth. Now, most of data hiding algorithms are still applied in 8-bit depth medical images. We proposed a histogram shifting method for image reversible data hiding testing on high bit depth medical images. Among image local block pixels, we exploit the high correlation for smooth surface of anatomical structure in medical images. Thus, we apply a different value for each block of pixels to produce a difference histogram to embed secret bits. During data embedding stage, the image blocks are divided into two categories due to two corresponding embedding strategies. Via an inverse histogram shifting mechanism, the original image will be accurately recovered after the hidden data extraction. Due to requirements of medical images for data hiding, we proposed six criteria: (1) well-suited for high quality medical images, (2) without salt-and-pepper, (3) applicable to medical image with smooth surface, (4) well-suited sparse histogram of intensity levels, (5) free location map, (6) ability of adjusting data embedding capacity, PSNR and Inter-Slice PSNR. We proposed a data hiding methods satisfying above 6 criteria.

Robust Patchwork-Based Embedding and Decoding Scheme for Digital Audio Watermarking

This paper presents a novel patchwork-based embedding and decoding scheme for digital audio watermarking. At the embedding stage, an audio segment is divided into two subsegments and the discrete cosine transform (DCT) coefficients of the subsegments are computed. The DCT coefficients related to a specified frequency region are then partitioned into a number of frame pairs. The DCT frame pairs suitable for watermark embedding are chosen by a selection criterion and watermarks are embedded into the selected DCT frame pairs by modifying their coefficients, controlled by a secret key. The modifications are conducted in such a way that the selection criterion used at the embedding stage can be applied at the decoding stage to identify the watermarked DCT frame pairs. At the decoding stage, the secret key is utilized to extract watermarks from the watermarked DCT frame pairs. Compared with existing patchwork watermarking methods, the proposed scheme does not require information of which frame pairs of the watermarked audio signal enclose watermarks and is more robust to conventional attacks.