Receiver Operating Characteristic (ROC) Graph to Determine the Most Suitable Pairs Analysis Threshold Value

Steganography is the art of hiding the information that is going to be sent from one party to another. Information can be hidden into image, text, audio or video. Steganography allowed communication to happen without other people notice there is transmission of message except the intended party. This paper explains the implementation of receiver operating characterictic (ROC) graph addressing the incorrect classification of images for stegogramme and non-stegogramme classes using pairs analysis detection technique. The threshold value to discriminate between the two classes is identified, to reduce the rate of false negative (FN)

OR-Benchmark: An Open and Reconfigurable Digital Watermarking Benchmarking Framework

Benchmarking digital watermarking algorithms is not an easy task because different applications of digital watermarking often have very different sets of requirements and trade-offs between conflicting requirements. While there have been some general-purpose digital watermarking benchmarking systems available, they normally do not support complicated benchmarking tasks and cannot be easily reconfigured to work with different watermarking algorithms and testing conditions. In this paper, we propose OR-Benchmark, an open and highly reconfigurable general-purpose digital watermarking benchmarking framework, which has the following two key features: 1) all the interfaces are public and general enough to support all watermarking applications and benchmarking tasks we can think of; 2) end users can easily extend the functionalities and freely configure what watermarking algorithms are tested, what system components are used, how the benchmarking process runs, and what results should be produced. We implemented a prototype of this framework as a MATLAB software package and demonstrate how it can be used in three typical use cases. The first two use cases show how easily we can define benchmarking profiles for some robust image watermarking algorithms. The third use case shows how OR-Benchmark can be configured to benchmark some image watermarking algorithms for content authentication and self-restoration, which cannot be easily supported by other digital watermarking benchmarking systems

Reproducibility of exhaled nitric oxide in smokers and non-smokers: relevance for longitudinal studies

<p>Abstract</p> <p>Background</p> <p>Currently, there is much interest in measuring fractional exhaled nitric oxide (<b>FE_NO</b>) in populations. We evaluated the reproducibility of <b>FE_NO</b>in healthy subjects and determined the number of subjects necessary to carry out a longitudinal survey of <b>FE_NO</b>in a population containing smokers and non-smokers, based on the assessed reproducibility.</p> <p>Methods</p> <p>The reproducibility of <b>FE_NO</b>was examined in 18 healthy smokers and 21 non-smokers. <b>FE_NO</b>was assessed once at 9 AM on five consecutive days; in the last day this measurement was repeated at 2 PM. Respiratory symptoms and medical history were assessed by questionnaire. The within- and between-session repeatability of <b>FE_NO</b>and log-transformed <b>FE_NO</b>was described. The power of a longitudinal study based on a relative increase in <b>FE_NO</b>was estimated using a bilateral t-test of the log-transformed <b>FE_NO</b>using the between-session variance of the assay.</p> <p>Results</p> <p><b>FE_NO</b>measurements were highly reproducible throughout the study. <b>FE_NO</b>was significantly higher in males than females regardless of smoking status. <b>FE_NO</b>was positively associated with height (p < 0.001), gender (p < 0.034), smoking (p < 0.0001) and percent FEV₁/FVC (p < 0.001) but not with age (p = 0.987). The between-session standard deviation was roughly constant on the log scale. Assuming the between-session standard deviation is equal to its longitudinal equivalent, either 111 or 29 subjects would be necessary to achieve an 80% power in detecting a 3% or a 10% increase in <b>FE_NO</b>respectively.</p> <p>Conclusion</p> <p>The good reproducibility of <b>FE_NO</b>is not influenced by gender or smoking habits. In a well controlled, longitudinal study it should allow detecting even small increases in <b>FE_NO</b>with a reasonable population size.</p

Semi-fragile Watermarking and Authentication for Law Enforcement Applications

In this paper, a semi-fragile watermarking method for authentication of law enforcement images such as digital images captured at crime scenes and traffic enforcement situations is proposed using the pinned sine transform (PST). The watermarking system can localize the portions of image that have been tampered maliciously, with high accuracy. In particular, the watermarking scheme is very sensitive to any texture alteration in the watermarked images, which is crucial for crime scene image authentication. Simulation results are presented to demonstrate the effectiveness of the proposed method and its possible applications in the field of crime scene analysis. The proposed method of watermarking authentication could potentially prove useful when digital photographs are presented as evidence in the court of law

An introduction to robust transform based image watermarking techniques

One of the important applications of digital watermarking technology is copyright protection and ownership identification for digital images. To achieve this goal, robust watermarking has been rapidly developed in the past decade or so. Robust watermarking is designed to survive various non-geometric manipulations such as JPEG compression, additive noise and filtering as well as some geometric distortions such as rotation and scaling. In this chapter, the fundamental concept of digital watermarking, differences between visible and invisible watermarking, blind and non-blind watermark detection schemes, robust, fragile and semi-fragile watermarking algorithms, as well as four important properties for digital watermarking: imperceptibility, robustness, capacity and security will be described. A number of different transforms and algorithms used for robust image watermarking will be reviewed in detail. These include block based Discrete Cosine Transform (DCT), non-block based Discrete Wavelet Transform (DWT) and other state-of-the-art watermarking algorithms operating in the transform domain. In contrast to conventional transform domain methods, a new adaptive robust watermarking algorithm using the non-redundant contourlet transform known as the wavelet-based contourlet transform (WBCT) is presented in this chapter. From experiments, we exploit the energy relations between parent and children coefficients, which are invariant before and after JPEG compression. Results show that even for QF set as low as 10, the percentages of invariant energy relations of all test images were above 75% after JPEG compression. This invariance feature is therefore very useful for robust image watermarking. The results of WBCT also are evaluated and compared with two other DWT based algorithms achieving high degree of robustness against most non-geometrical and geometrical attacks, while maintaining an excellent perceptual invisibility. © 2010 Springer-Verlag Berlin Heidelberg

Semi-fragile Watermarking, Authentication and Localisation Techniques for Law Enforcement Applications

With the tremendous growth and use of digital cameras and video devices, the need to verify the collected digital content for law enforcement applications such as crime scene investigations and traffic violations, becomes paramount if they are to be used as evidence in courts. Semi-fragile watermarking has become increasingly important within the past few years as it can be used to verify the content of images by accurately localising the tampered area and tolerating some non-malicious manipulations. There have been a number of different transforms used for semi-fragile image watermarking. In this chapter, we present two novel transforms for semi-fragile watermarking, using the Slant transform (SLT) as a block-based algorithm and the wavelet-based contourlet transform (WBCT) as a non-block based algorithm. The proposed SLT is compared with existing DCT and PST semi-fragile watermarking schemes. Experimental results using standard test images and simulated law enforcement images indicate that the SLT is more accurate for copy and paste attacks with non-malicious manipulations, such as additive Gaussian noise. For the proposed WBCT method, watermarking embedding is performed by modulating the parent-children relationship in the contourlet domain. Again, experimental results using the same test images have demonstrated that our proposed WBCT method achieves good performances in localising the tampered regions, even when the image has been subjected to non-malicious manipulations such as JPEG/JPEG2000 compressions, Gaussian noise, Gaussian filtering, and contrast stretching. The average miss detection rate is found to be approximately 1% while maintaining an average false alarm rate below 6.5%