Grayscale Watermark Research Articles

Combining double random phase encoding for color image watermarking in quaternion gyrator domain

Quaternion representation of color image has attracted great attention due to its capability to treat holistically the three color channels. In a more general way, it has successfully been used in multi-channel signal processing applications over the past few decades. In this study, a joint encryption/watermarking system with more security based on double random phase encoding (DRPE) in quaternion gyrator transform domain is addressed. In the proposed scheme, an RGB-scale watermark image together with a grayscale watermark image or not is encoded into a quaternion matrix and encrypted through the DRPE, the encrypted data is then fused into the middle coefficients of the quaternion gyrator-transformed host image. In the process of extracting watermarks, it is impossible to retrieve them without authorized keys. Compared with the three channels independently processing approach implemented in fractional Fourier domain, the proposed algorithm achieves lower complexity by reason of avoiding repetitive operations. Experimental results have demonstrated the feasibility of the proposed algorithm and its superior performance in terms of noise robustness.

Discrete wavelet transform-based color image watermarking using uncorrelated color space and artificial bee colony

AbstractThe exponential growth in electronic data over internet have increased the demand of a robust and high quality watermarking method for authentication and copyright protection. In general, the existing digital image watermarking methods embed the binary or gray scale watermark into the host image although most multimedia images are available in color. Moreover, available digital image watermarking methods generally use the correlated color spaces which impose the limitations to researchers for using only one color component at a time for embedding the watermark. Therefore, in this paper, a novel discrete wavelet transform (DWT) based color image watermarking method has been proposed which embeds the color watermark into host image using uncorrelated color space (UCS) and artificial bee colony (ABC) method. The results show that proposed method outperforms other existing methods against the various signal processing attacks.

Security analyses of the watermarking scheme based on redundant discrete wavelet transform and singular value decomposition

This study analyzes the recent image watermarking schemes based on redundant discrete wavelet transform (RDWT) and singular value decomposition (SVD), and shows that in fact they are insecure and cannot be used for protecting the rightful ownership. The RDWT-SVD watermarking directly embeds a grayscale watermark image of the same size with the host image into the singular value matrix of the RDWT-transformed host image, then produces the left and right orthogonal matrices as side information which is later used in the watermark extraction stage. The RDWT-SVD approach enjoys the advantage of the RDWT redundancy to achieve a high embedding capacity, and preserves the watermark imperceptibility by exploiting the SVD stability properties. It is claimed that RDWT-SVD watermarking is robust against several common image processing and geometrical attacks, yet a fundamental flaw in the RDWT-SVD scheme is found, which leads to severe the false positive issue. Three vulnerable attacks should be considered in the RDWT-SVD scheme: (1) An attacker can easily claim the owner watermarked image; (2) the owner has the ambiguity because of the wrong side information usage, and (3) the owner can extract the correct watermark from arbitrary image. Thus, it is important to highlight these attacks when implementing the RDWT-SVD watermarking scheme.

Robust logo watermarking using biometrics inspired key generation

In this paper, a novel logo watermarking technique with key concept is proposed using fractional wavelet packet transform (FrWPT), non-linear chaotic map and singular value decomposition (SVD). The core idea is to use biometrically generated keys in the embedding process of gray-scale watermark. Therefore, this paper first proposes a method for generating keys from biometrics efficiently. Then the host image is first randomized with the help of non-linear chaotic map followed by the embedding in the FrWPT domain by modifying the singular values of the randomized image. Further, in order to enhance the security, an authentication key is formed to authenticate the watermarked image. Finally, a reliable extraction process is proposed to extracted watermark from the possibly attacked authenticate watermarked image. The security, attack and comparative analysis confirm high security, efficiency and robustness of the proposed watermarking technique. Further, an efficient solution is also proposed to deal with the ambiguous situations created by SVD in watermarking.

A Novel Image Watermarking Scheme Based on MCA Neural Networks

Minor component analysis (MCA) plays an important role in signal processing and data analysis. In this paper, we propose a novel watermarking scheme using MCA neural networks. The proposed scheme can detect and localize any modification made to the image, which can be used for integrity verification and authentication. Another important property of this proposed scheme is that any gray scale watermark can be easily inserted into the image compared to some other watermarking method such as LSB (least significant bit) method. Furthermore, the proposed scheme can insert any watermark into one image without making any visible changes to the image. Since the minor component of each image is different, and it requires a user key during both the insertion and extraction procedures, it is not possible for an infringer to insert a new watermark or alter the existing one that could pass the test. Finally, various experiments also confirm such properties of the proposed scheme.

Adaptive Hybrid Video Watermarking using WBCT and NMF

techniques are mainly used for protecting intellectual property right. This paper proposes a new hybrid nonblind video watermarking technique using wavelet contourlet transform and nonnegative matrix factorization Wavelet transform processed images are losing edge information. The Contourlet transform has good approximation properties for smooth 2D functions and finds a direct discrete space construction. But its performance is considered to be redundant. There evolved wavelet based contourlet transform (WBCT), as a nonredundant version of the contourlet transform. WBCT is used for watermarking video frames. The non negative matrix factorization (NMF) is used as dimension reduction technique in watermarking. NMF is applied to low pass and directional high pass sub bands which results from WBCT of each original video frame and gray scale watermark images. Embedding action is performed in low pass sub-band of WBCT processed video frame. The hybrid scheme improves the performance of watermarking scheme. The experimental results shows that the proposed video watermarking scheme provides better video processing operations such as cropping, rotation, histogram equalization ,compression, variety of noises , frame dropping, frame averaging and frame swapping and etc.

Secured and Distortion Less Gray-Scale Medical Image Watermarking Scheme

Secured and Distortion Less Gray-Scale Medical Image Watermarking Scheme

Biometrics inspired watermarking based on a fractional dual tree complex wavelet transform

In this paper, a novel biometrics inspired watermarking technique is proposed. For this purpose, a newly proposed mathematical transform, namely the fractional dual tree complex wavelet transform (FrDT-CWT), and singular value decomposition (SVD) are used. The core idea is to use biometrically generated keys in the embedding process of a gray-scale watermark. Therefore, this paper first proposes a method for generating keys from biometrics efficiently. The host image is first randomized by Hessenberg decomposition and a chaotic map, followed by embedding in the FrDT-CWT domain by modifying the singular values of the randomized image. Further, in order to prevent the ambiguity problem of SVD-based techniques, a verification step is introduced to verify the watermarked image. Finally, a reliable extraction process is proposed to extract the watermark from the possibly attacked watermarked image after verification. The security, attack, and comparative analysis confirms the high security, efficiency, and robustness of the proposed watermarking technique.

A new facet in robust digital watermarking framework

Generally, in watermarking techniques the size of the watermark is very small when compared to the host image. On the contrary, this is an attempt in which a new facet in watermarking framework is presented where the size of host image is very small when compared to the watermark image. The core idea of the proposed technique is to first scale up the size of host image equal to the size of watermark using chaotic map and Hessenberg decomposition followed by the redundant wavelet transform. A meaningful gray scale watermark is embedded in the low frequency sub-band at the finest level using singular value decomposition. To prevent ambiguity and enhance the security, a binary watermark is also embedded in loss-less manner which ensures the authenticity of the watermarked image. Finally, a reliable watermark extraction scheme is developed for extracting both the watermarks. The experimental results demonstrate better visual imperceptibility and resiliency of the proposed scheme against intentional or un-intentional variety of attacks.

A new aspect in robust digital watermarking

Generally, in watermarking scheme the size of the watermark is very small when compare to host image. On the contrary, this is an attempt in which a new watermarking scheme is presented where the size of host image is very small when compare with watermark image. The core idea of the proposed scheme is to scale up the size of host image equal to the size of watermark via over-sampling and then decompose it using stationary wavelet transform. A gray scale watermark is embedded in the low frequency sub-band at the finest level using singular value decomposition. To prevent ambiguity and enhance the security, a binary watermark is also embedded in loss-less manner. Finally, a reliable watermark extraction scheme is developed for extracting both the watermarks. The experimental results demonstrate better visual imperceptibility and resiliency of the proposed scheme against intentional or un-intentional variety of attacks.

A Robust Grayscale Watermarking Algorithm

In this paper, a novel robust grayscale watermarking algorithm based on Two-Levels DCT and SVD is proposed. The watermark signal is (32× 32 × 8) bit gray image. First, the original image is divided into blocks according to the size of the watermark; each block corresponds to each pixel value of watermark. Second, the DCT is applied in each block twice and form new blocks. Then, Get the largest value of each new block to form a new matrix .Apply SVD on the new matrix to get matrices U, S and V for each block. The pixel value of watermark is embedded into the S matrix of the new matrix. And the watermark can be detected with the original image. The experimental results show that the algorithm can satisfy the transparence and robustness of the watermarking system very well. Experimental evaluation demonstrates that the proposed scheme is able to withstand a variety of attacks very well.

A New Robust Watermarking Scheme to Increase Image Security

In digital image watermarking, an image is embedded into a picture for a variety of purposes such as captioning and copyright protection. In this paper, a robust private watermarking scheme for embedding a gray-scale watermark is proposed. In the proposed method, the watermark and original image are processed by applying blockwise DCT. Also, a Dynamic Fuzzy Inference System (DFIS) is used to identify the best place for watermark insertion by approximating the relationship established between the properties of HVS model. In the insertion phase, the DC coefficients of the original image are modified according to DC value of watermark and output of Fuzzy System. In the experiment phase, the CheckMark (StirMark MATLAB) software was used to verify the method robustness by applying several conventional attacks on the watermarked image. The results showed that the proposed scheme provided high image quality while it was robust against various attacks, such as Compression, Filtering, additive Noise, Cropping, Scaling, Changing aspect ratio, Copy attack, and Composite attack in comparison with related methods.

Nonblind and Quasiblind Natural Preserve Transform Watermarking

This paper describes a new image watermarking technique based on the Natural Preserving Transform (NPT). The proposed watermarking scheme uses NPT to encode a gray scale watermarking logo image or text, into a host image at any location. NPT brings a unique feature which is uniformly distributing the logo across the host image in an imperceptible manner. The contribution of this paper lies is presenting two efficient nonblind and quasiblind watermark extraction techniques. In the quasiblind case, the extraction algorithm requires little information about the original image that is already conveyed by the watermarked image. Moreover, the proposed scheme does not introduce visual quality degradation into the host image while still being able to extract a logo with a relatively large amount of data. The performance and robustness of the proposed technique are tested by applying common image-processing operations such as cropping, noise degradation, and compression. A quantitative measure is proposed to objectify performance; under this measure, the proposed technique outperforms most of the recent techniques in most cases. We also implemented the proposed technique on a hardware platform, digital signal processor (DSK 6713). Results are illustrated to show the effectiveness of the proposed technique, in different noisy environments.

An Image Authentication Based on Discrete Fourier Transform

The advances of network technologies and digital devices facilitate users to exchange multimedia data over the public networks. However, this also raises significant concerns about how to protect sensitive multimedia data from being illegally copied and unauthorized modifications. Thus, this paper proposes a fragile watermarking method to detect illegitimate alterations of the watermarked data. The proposed method embeds a grayscale watermark image into a grayscale cover image in a block-by-block manner by using discrete Fourier transform. Experimental results show that the proposedmethod can successfully and exactly detect and localize any tampered regions of the watermarked image.

HDWT-based grayscale watermark for copyright protection

We propose a new algorithm based on Harr discrete wavelet transform for the grayscale watermark. Digital watermark is a very popular research for copyright protection of electronic documents and media. With quick developing of information technology, more and more information was been hidden in electronic media. We propose visual cryptographic approach to generate two random shares of a watermark: one is embedded into the cover-image, another one is kept as a secret key for the watermark extraction later. This procedure would be dealt with Harr discrete wavelet transform and be left primary features of two shares. This approach is specially designed and is not easily changed and removed. After several attacks, it can still extract cognoscible graphic.

An Embedding Scheme for Binary and Grayscale Watermarks by Spectrum Spreading and Its Performance Analysis

Digital watermarking is a technique that aims at hiding a message signal in a multimedia signal for copyright claim, authentication, device control, or broadcast monitoring, etc. In this paper, we focus on embedding watermarks into still images, where the watermarks themselves can be binary sequences or grayscale images. We propose to scramble the watermark bits with pseudo-noise (PN) or orthogonal codes before they are embedded into an image. We also try to incorporate error correction coding (ECC) into the watermarking scheme, anticipating reduction of the watermark bit error rate (WBER). Due to the similarity between the PN/orthogonal-coded watermarking and the spread spectrum communication, it is natural that, following similar derivations regarding data BER in digital communications, we derive certain explicit quantitative relationships regarding the tradeoff between the WBER, the watermark capacity (i.e. the number of watermark bits) and the distortion suffered by the original image, which is measured in terms of the embedded image's signal-to-noise ratio (abbreviated as ISNR). These quantitative relationships are compactly summarized into a so-called tradeoff triangle, which constitutes the major contribution of this paper. For the embedding of grayscale watermarks, an unequal error protection (UEP) scheme is proposed to provide different degrees of robustness for watermark bits of different degrees of significance. In this UEP scheme, optimal strength factors for embedding different watermark bits are sought so that the mean squared error suffered by the extracted watermark, which is by itself a grayscale image, is minimized while a specified ISNR is maintained.

Robust Video Watermarking of H.264/AVC

A robust video watermarking scheme of the state-of-the-art video coding standard H.264/AVC is proposed in this brief. 2-D 8-bit watermarks such as detailed company trademarks or logos can be used as inconvertible watermark for copyright protection. A grayscale watermark pattern is first modified to accommodate the H.264/AVC computational constraints, and then embedded into video data in the compressed domain. With the proposed method, the video watermarking scheme can achieve high robustness and good visual quality without increasing the overall bit-rate. Experimental results show that our algorithm can robustly survive transcoding process and strong common signal processing attacks, such as bit-rate reduction, Gaussian filtering and contrast enhancement

Dual-wrapped digital watermarking scheme for image copyright protection

Digital watermarking is an effective way to protect the rightful ownership of multimedia contents. In this paper, a two-phase watermarking scheme is proposed, which extracts both the grayscale watermark and the binary one from the protected images to achieve the copyright protection goal. In the first phase, the proposed method utilizes the pixel values of the original image to construct a grayscale watermark image. In the second phase, a binary watermark image can be further retrieved via the just-procured-permuted grayscale watermark from the first phase. Under these circumstances, the proposed technique results in lossless embedding; in other words, the protected images are the same as the original ones. The overall verification procedure does not need the original image. Only those who have the original grayscale watermark and the corresponding secret keys can extract the grayscale and binary watermarks sequentially, which enhances security and robustness of the proposed watermarking system. Experimental results show that the proposed approach satisfies the general requirements of image watermarking and is superior to related methods in terms of transparency and robustness. Moreover, it is easier to be implemented than transform-domain techniques. These flexible features make the proposed method more feasible and practical for copyright protection.

A semi-blind digital watermarking scheme based on singular value decomposition

This paper presents a robust watermarking approach for hiding grayscale watermarks into digital images. Plugging the codebook concept into the singular value decomposition (SVD), the proposed method embeds the singular values (SVs) of the original image into the watermark one to attain the lossless objective. The experimental results show that the proposed scheme guarantees the extracted watermark on an average and the worst PSNR values of 24.91 and 19.96 dB, respectively. In addition to the guarantee of the quality of extracted watermark image, the security of the referenced watermark is further strengthened by applying chaos permutation on it in advance. The proposed scheme leads to satisfactory robustness to various attacks and is compared to other well-known grayscale watermarking methods to reveal its efficiency for practical applications.