Quality Of Watermarked Image Research Articles

Secured Biometric Authentication using Visual Cryptography and Transforms

ection of biometric data is gaining importance because its uniqueness and digital watermarking techniques are used to protect the biometric data from either accidental or intentional attacks. Here introduces a novel secured authentication method using wavelet decomposition and Visual Cryptography to hide an iris image. In this report gives exhaustive study on a scheme in which iris image is secured by using a technique called Visual Cryptography (VC). In this technique, iris image is embedded in cover image and then using wavelet transform this output image is decomposed into four shares. These four shares are compressed at sender site. At receiver side, to obtain original iris image inverse DWT is obtained and finally bit matching procedure has been applied. The result shows that Stegnography and Visual cryptography implementation on biometrics, secures Iris and related textual information from getting identity forged. In comparison with existing approach quality of final watermarked cover images and Iris has been maintained which could be used for matching of it for authentication. Along with quality, goal of higher security and bandwidth reduction by reducing size of shares is achieved. Also technique of three least significant bits applied successfully that allows secret message of increased length by maintaining quality of Iris. KeywordsLeast Significant Bit (SLSB) Method, LSB, Visual

Reversible watermarking method based on asymmetric-histogram shifting of prediction errors

This paper tries to provide a new perspective for the research of reversible watermarking based on histogram shifting of prediction errors. Instead of obtaining one prediction error for the current pixel, we calculate multiple prediction errors by designing a multi-prediction scheme. An asymmetric error histogram is then constructed by selecting the suitable one from these errors. Compared with traditional symmetric histogram, the asymmetric error histogram reduces the amount of shifted pixels, thus improving the watermarked image quality. Moreover, a complementary embedding strategy is proposed by combining the maximum and minimum error histograms. As the two error histograms shift in the opposite directions during the embedding, some watermarked pixels will be restored to their original values, thus the image quality is further improved. Experimental findings also show that the proposed method re-creates watermarked images of higher quality that carry larger embedding capacity compared to conventional symmetric histogram methods, such as Tsai et al.’s and Luo et al.’s works.

DS-DPSO: A dual surrogate approach for intelligent watermarking of bi-tonal document image streams

Intelligent watermarking (IW) techniques employ population-based evolutionary computing in order to optimize embedding parameters that trade-off between watermark robustness and image quality for digital watermarking systems. Recent advances indicate that it is possible to decrease the computational burden of IW techniques in scenarios involving long heterogeneous streams of bi-tonal document images by recalling embedding parameters (solutions) from a memory based on Gaussian Mixture Model (GMM) representation of optimization problems. This representation can provide ready-to-use solutions for similar optimization problem instances, avoiding the need for a costly re-optimization process. In this paper, a dual surrogate dynamic Particle Swarm Optimization (DS-DPSO) approach is proposed which employs a memory of GMMs in regression mode in order to decrease the cost of re-optimization for heterogeneous bi-tonal image streams. This approach is applied within a four level search for near-optimal solutions, with increasing computational burden and precision. Following previous research, the first two levels use GMM re-sampling to recall solutions for recurring problems, allowing to manage streams of heterogeneous images. Then, if embedding parameters of an image require a significant adaptation, the third level is activated. This optimization level relies on an off-line surrogate, using Gaussian Mixture Regression (GMR), in order to replace costly fitness evaluations during optimization. The final level also performs optimization, but GMR is employed as a costlier on-line surrogate in a worst-case scenario and provides a safeguard to the IW system. Experimental validation were performed on the OULU image data set, featuring heterogeneous image streams with a varying levels of attacks. In this scenario, the DS-DPSO approach has been shown to provide comparable level of watermarking performance with a 93% decline in computational cost compared to full re-optimization. Indeed, when significant parameter adaptation is required, fitness evaluations may be replaced with GMR.

Partially compressed-encrypted domain robust JPEG image watermarking

Digital media is often handled in a compressed and encrypted form in Digital Asset Management Systems. And watermarking of the compressed encrypted media items in the compressed-encrypted domain itself is required sometimes for copyright violation detection or other purposes. In this paper, we propose a robust image watermarking technique for partially compressed-encrypted JPEG images. However, arbitrary embedding of a watermark in a partially compressed encrypted image can cause drastic degradation of the quality as the underlying change may result in random decrypted values. In addition, due to the encryption the compression efficiency may become very low. Thus the challenge is to design a watermarking technique that provides good watermarked image quality and at the same time gives good compression efficiency. While the proposed technique embeds watermark in the partially compressed-encrypted domain, the extraction of watermark can be done in the encrypted or decrypted domains. The experiments show that the watermarked image quality is good and the reduction in compression efficiency is low. The proposed watermarking technique is robust to common signal processing attacks. The watermark detection performance of the proposed scheme is better than the existing encrypted domain watermarking techniques.

Reversible Watermark Using an Accurate Predictor and Sorter Based on Payload Balancing

A series of reversible watermarking technologies have been proposed to increase embedding capacity and the quality of the watermarked image simultaneously. The major skills include difference expansion, histogram shifting, and optimizing embedding order. In this paper, an accurate predictor is proposed to enhance the difference expansion. An efficient sorter is also suggested to find a more desirable embedding order. The payload is differently distributed into two sub-images, split like a chessboard pattern, for better watermarked image quality. Simulation results of the accurate prediction and sorter based on the payload balancing method yield generally better performance over previous methods. The gap is wide, in particular, in low payload for natural images. The peak signal-to-noise ratio improvement is around 2 dB in low payload ranges.

Securing Fingerprint Images Through PSO Based Robust Facial Watermarking

Presented is an efficient watermarking scheme using Particle Swarm Optimization (PSO) to watermark host fingerprint images with their corresponding facial images in the Discrete Cosine Transform (DCT) domain. PSO is used to find the best DCT coefficients’ locations in the host image where the facial image data can be embedded, so that the distortion produced in the host image is minimum. The objective function for PSO is formulated in terms of the Structural Similarity Index (SSIM) and the Orientation Certainty Level Index (OCL) so as to base it on the simple visual effect of the human visual perception capability and correct minutia prediction ability. The results exhibit better watermarked image quality while retaining the feature set of the original fingerprint. Moreover, the proposed technique is robust so that the extraction of watermark is possible even after the watermarked image is exposed to attacks. As a result, at the receiver’s end, the watermarked fingerprint image and the extracted facial image can be verified for a secure and accurate biometric based personal authentication.

Reversible watermarking schemes based on expansion embedding using pixel partition strategies

Reversible watermarking methods have drawn attention of many researchers in recent years because original cover objects can be completely restored upon extraction of embedded information. The prediction error expansion (PEE) embedding proposed by Thodi and Rodriguez can embed one information bit into one cover pixel and achieve good visual quality of watermarked images. However, the PEE method is not a generalised scheme and its embedding capacity measured by bit per pixel (bpp) and visual quality measured by peak signal-to-noise ratio (PSNR) can be improved. Thus, we propose two novel schemes based on the PEE method by using pixel partition strategies to improve embedding capacity and/or visual quality. The first proposed scheme makes the PEE method be generalised and the second proposed scheme can embed more than 1 bpp. Experimental results show that the proposed schemes can significantly improve visual quality of the watermarked images produced by the PEE method when embedding capacity falls within the range [0·1, 1]. In particular, when an embedding capacity belongs to the range [0·1, 0·5], in average, the first proposed scheme with K = 1 can improve the PSNR of the PEE method at least 13 dB for test images. In addition, when embedding capacity falls within the range [0·1, 1], in average, the second proposed scheme with K = 1 can improve the PSNR of the PEE method at least 14 dB for test images.

Hybrid watermarking of medical images for ROI authentication and recovery

Medical image data require strict security, confidentiality and integrity. To achieve these stringent requirements, we propose a hybrid watermarking method which embeds a robust watermark in the region of non-interest (RONI) for achieving security and confidentiality, while integrity control is achieved by inserting a fragile watermark into the region of the interest (ROI). First the information to be modified in ROI is separated and is inserted into RONI, which later is used in recovery of the original ROI. Secondly, to avoid the underflow and overflow, a location map is generated for embedding the watermark block-wise by leaving the suspected blocks. This avoids the preprocessing step of histogram modification. The image visual quality, as well as tamper localization, is evaluated. We use weighted peak signal to noise ratio for measuring image quality of watermarked images. Experimental results show that the proposed method outperforms the existing hybrid watermarking techniques.

Tabu search based multi-watermarks embedding algorithm with multiple description coding

Digital watermarking is a useful solution for digital rights management systems, and it has been a popular research topic in the last decade. Most watermarking related literature focuses on how to resist deliberate attacks by applying benchmarks to watermarked media that assess the effectiveness of the watermarking algorithm. Only a few papers have concentrated on the error-resilient transmission of watermarked media. In this paper, we propose an innovative algorithm for vector quantization (VQ) based image watermarking, which is suitable for error-resilient transmission over noisy channels. By incorporating watermarking with multiple description coding (MDC), the scheme we propose to embed multiple watermarks can effectively overcome channel impairments while retaining the capability for copyright and ownership protection. In addition, we employ an optimization technique, called tabu search, to optimize both the watermarked image quality and the robustness of the extracted watermarks. We have obtained promising simulation results that demonstrate the utility and practicality of our algorithm.

Semi-blind Watermarking Scheme Exploiting Self-Reference Image

This work presents a semi-blind watermark scheme exploiting a self-reference image for digital image protection and authenticity. The proposed scheme is feasible for practical applications since extraction and detection procedures do not require the original image. To improve robustness and reduce the computational cost of embedding or extracting the watermark, in the proposed scheme, the original image is initially transfromed into wavelet coefficients using one-level discrete wavelet transform (DWT) and then three high-frequency sub-bands, i.e., LH1, HL1 and HH1, are set as zero. A corresponding self-reference image can thus be obtained after performing the inversed DWT. The watermark is embedded into a specific difference value between the original image and the self-reference image by using just noticeable distortion (JND) approach. Experimental results indicate that the proposed scheme provides the high visual quality of the watermarked image and leads to satisfactory robustness to various attacks, including cropping, blurriness, brightness, noise interference, sharpening, and JEPG lossy compression. Moreover, the proposed scheme enhances the security capability of Liu et al.'s scheme to resist the attack with Ting et al's scheme.

Digital Watermarking Method Warranting the Lower Limit of Image Quality of Watermarked Images

We propose a digital watermarking method warranting the lower limit of the image quality of watermarked images. The proposed method controls the degradation of a watermarked image by using a lower limit image. The lower limit image means the image of the worst quality that users can permit. The proposed method accepts any lower limit image and does not require it at extraction. Therefore lower limit images can be decided flexibly. In this paper, we introduce 2-dimensional human visual MTF model as an example of obtaining lower limit images. Also we use JPEG-compressed images of quality 75% and 50% as lower limit images. We investigate the performance of the proposed method by experiments. Moreover we compare the proposed method using three types of lower limit images with the existing method in view of the trade off between PSNR and the robustness against JPEG compression.

Error-Resilient Triple-Watermarking with Multiple Description Coding

W atermarking is one useful solution for digital rights management (DRM) systems , and it is a popular research topic in the last decade . In this paper, besides the inherent behavior to conquer against intentional or unintentional attacks for watermarking, we not only watch the survivability of embedded watermark, but also focus on retaining the watermarked image quality with the aid of multiple description coding (MDC). MDC is a technique for error resilient coding, suitable for transmitting compressed data over multiple channels. In this paper, we propose a n ew algorithm on vector quantization (VQ) based image watermarking, which is suitable for error-resilient transmission. By incorporating watermarking with MDC , the scheme we proposed for embedding three watermarks can effectively overcome channel impairments while retaining the capability for ownership protection. With the promising simulation results presented, we can demonstrate the utility and practicability of our algorithm.

Reversible Watermarking Method for JPEG Images

In this letter, we propose a simple reversible watermarking method for JPEG images using the characteristics of JPEG compression. The method embeds a watermark into a JPEG image, and it extracts the watermark from the watermarked JPEG image and at the same time can recover the watermarked JPEG image to an original unwatermarked JPEG image. Moreover we investigate the number of embeddable blocks, the quality of watermarked images, and the increase of file-size by embedding a watermark.

Visual quality of watermarking for mobile devices

Abstract— In this study, the visual quality of watermarked images, displayed on mobile devices, are evaluated. A watermarking technique in the spatial domain where a watermark is embedded into an image is considered. Three different types of images are considered and for each image five values of watermarking magnitude were tested. The difference in human evaluation of visual quality of a watermarked image, depending upon image properties and the properties of a display was evaluated. In visual assessment tests, images from a mobile phone, PDA, and CRT were used. The visual quality of watermarked image was evaluated by 20 human observers. The results were quantified using statistical testing. The results show that for high-end displays the magnitude used for watermarking is a critical factor in image quality. In mobile devices the magnitude used for watermarking has little visual effect, especially for technical drawings. Recommendations for proper parameters are given.

A new approach for optimization in image watermarking by using genetic algorithms

In this paper, the authors propose the spread spectrum image watermarking algorithm using the discrete multiwavelet transform. Performance improvement with respect to existing algorithms is obtained by genetic algorithms optimization. In the proposed optimization process, the authors search for parameters that consist of threshold values and the embedding strength to improve the visual quality of watermarked images and the robustness of the watermark. These parameters are varied to find the most suitable for images with different characteristics. The experimental results show that the proposed algorithm yields a watermark that is invisible to human eyes and robust to various image manipulations. The authors also compare their experimental results with the results of previous work using various test images.

Protecting patient privacy against unauthorized release of medical images in a group communication environment

In this paper, we identify and study an important patient privacy protection problem related to medical images. Following Health Insurance Portability and Accountability Act (HIPAA) mandate on privacy protection of patients' medical records, efforts have been devoted to guaranteeing the confidentiality of data and medical images during storage and transmission via an untrustworthy channel. However, to our knowledge, there has not been any effort towards protecting against unauthorized release of images by an authorized recipient. In this paper, we study the problem of tracing illegally distributed medical images in a group communication environment and identify a set of design requirements that must be met. We propose a fingerprint model suitable for many-to-many multicast, that is computationally efficient and scalable in user storage and key update communication. Simulation results also show that our scheme is highly robust to typical medical image processing and collusion attacks, while yielding high quality watermarked images.

Enhancement of image watermark retrieval based on genetic algorithms

A watermark hidden in an image is retrieved differently from the original watermark due to the frequently used rounding approach. The simple rounding will cause numerous errors in the embedded watermark especially when it is large. A novel technique based on genetic algorithms (GAs) is presented in this paper to correct the rounding errors. The fundamental is to adopt a fitness function for choosing the best chromosome which determines the conversion rule of real numbers into integers during the cosine transformation. Experimental results show that the dramatic improvement in reducing the errors is successful when GAs are used in decision making. Furthermore, we develop an initial chromosome by comparing the difference between the original image and the rounded watermarked image to speed up the process. In additional to correct fragile-watermarking rounding errors, our algorithm can also be applied in robust watermarking to achieve higher watermarked image quality.

Genetic watermarking based on transform-domain techniques

An innovative watermarking scheme based on genetic algorithms (GA) in the transform domain is proposed. It is robust against watermarking attacks, which are commonly employed in the literature. In addition, the watermarked image quality is also considered. In this paper, we employ GA for optimizing both the fundamentally conflicting requirements. Watermarking with GA is easy for implementation. We also examine the effectiveness of our scheme by checking the fitness function in GA, which includes both factors related to robustness and invisibility. Simulation results also show both the robustness under attacks, and the improvement in watermarked image quality with GA.

A cropping‐robust watermarking method based on singular value decomposition and Haar transformation

AbstractThis paper proposes a new watermarking method which applies SVD (singular value decomposition) to the watermark image and the Haar transformation to the host image, respectively. In this method, relatively important information which corresponds to larger singular values is embedded as near to the center of the low‐frequency component image of the Haar transformed host image as possible. This method is useful in decreasing degradation of the quality of watermarked host images and thus in making the embedded watermark robust to various attacks. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(9): 38–47, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10371