Digital Watermarking is used for the protection of the rights of the user. In this paper, a hybrid of DWT-SVD technique has been proposed to embed watermark in the image. The properties of DWT and SVD were found to be complementing each other as the proposed method reveals good transparency and robustness. During experimenting, the PSNR values for all test images above 30dB indicate good perceptual transparency of proposed algorithm. The experimental results also indicate that the proposed technique is robust against challenging image processing attacks with NCC closer to 1 and BER closer to 0. The comparative study of the proposed algorithm with existing literature has also been presented in this paper indicating effectiveness of the proposed algorithm.

A secure and robust image watermarking system using wavelet domain

In recent years chaos has received a great deal of attention from the researches specialized in communications, signal and image processing. The complexity property of the chaotic signal raised the idea of using such signals in secure communications. Digital image watermarking is a technique mainly developed for copyright protection and image authentication and it can be considered as one application area of the secure communication. In this study, a chaos based digital image watermarking algorithm based on redundant discrete wavelet transform (RDWT) and singular value decomposition (SVD) is proposed. To the best of our knowledge, there do not exist any digital watermarking scheme combining RDWT, SVD and chaos. Robustness and invisibility of the proposed method are improved by using the logistic mapping function to generate a chaotic image matrix serving as the watermark that is used to modify the singular values of the low frequency sub-band of the cover image obtained by applying RDWT. The method is shown to be robust against both the geometrical and image processing attacks and to provide better watermark concealment via computer simulations. Using a chaotic signal as the watermark allows the proposed scheme to meet the security requirements as well.

/pdf/robust-chaotic-digital-image-watermarking-scheme-based-on-4sxka2rc57.pdf

Robust Chaotic Digital Image Watermarking Scheme based on RDWT and SVD

Digital watermarking is a concept of embedding authentication information. It uses an algorithm for inserting a watermark to protect the copyright of media. It became very important in various application areas like video, audio, text, image etc... A number of watermark techniques have been proposed by many authors in the last several years. However, there is a need to have enough analysis and comparative study on these techniques. This paper has discussed the conventional watermark techniques from various points of view. Currently watermark techniques based on the transform domain are more popular than those of the spatial domain.

/pdf/study-of-contemporary-digital-watermarking-techniques-3bffq1ik19.pdf

Study of contemporary digital watermarking techniques

In the last years the subject of hiding information has been effective, and steganography is one of the most important subdisciplines. Many of the algorithms appeared to work on developing efficient techniques of practical steganography. Steganography is the science that deals with hiding of secret data in some carrier media which may be image, audio, formatted text or video. The main idea behind this is to conceal the very existence of data. We deal here with image steganography. This work presents techniques of image steganography (Blind and non-Blind) based on chaotic system and Contourlet Transform, the chaotic system is used due to many properties; first of all using a Modified Arnold Cat Map( MACM ) to increase the key space which makes it very difficult to extract the secret message by the enemy. In this method, embedding is done in Contourlet domain that provides large embedding capacity, after that the correct location of embedding would be selected carefully to decrease the distortion on the cover image to avoid the detection of this process. Experiments and comparative studies showed the effectiveness of the proposed technique in generating stego images. In addition, its superiority is shown by comparison with a similar waveletbased steganography approach. The measurement of the quality of the stego image was depended on the PSNR, SNR and Correlation for measuring the similarity between the cover image and the stego image .

High capacity steganography based on chaos and contourlet transform for hiding multimedia data

To overcome the problem between invisibility and robustness,a robust digital watermarking scheme is proposed based on SVD relationship of wavelet coefficientsAs DWT of image has their own characteristics of high and low frequency bands to embed watermark,quantized steps of high and low frequency,which is combined with human visual system and local characteristics of images,are used to embed watermark adaptively through SVD relationship of each band wavelet coefficientsIt will combine and complement the advantages of high frequency and low frequency respectivelyExperimental results indicate this scheme is robust to common image attacks,including JPEG compression,noise,image cut and scaleMoreover,the scheme has the property of perceptual transparencyIt is a simple and feasible blind digital watermarking algorithm

Digital watermarking algorithm based on svd relationship of wavelet coefficients

This paper presents a new wavelet domain watermarking method, the carrier image using wavelet decomposition. After the Walsh transform low frequency wavelet coefficients, calculated by block adaptive embedding strength, modify the wavelet coefficients of each block, and then do singular value decomposition (SVD), repeat on embedded watermark in the singular value. Fractional part of the anti-transformed image is saved, correction of the watermarked image can be accurately extracted watermark. The experimental results demonstrate that the proposed algorithm can effectively resist cutting, scaling, translation and other geometric attacks, attacks in general are also robust.

Digital image watermarking robust to geometric attacks based on wavelet domain

This paper presents a stratified image hiding scheme based on chaotic algorithm. In the pretreatment process chaotic sequences are used to encrypt the secret image. The histogram of the processed image is similar to that of white noise. A stratified secret data embedding thought is adopted in the embedding process. As the experimental results show, this algorithm has relatively large embedding capacity, good invisibility and robustness.

A stratified image-hiding method based on chaos

Abstract. Black carbon (BC) is an important atmospheric component with strong light absorption. Many attempts have been made to measure BC mass size distribution (BCMSD) for its significant impact on climate and public health. Larger-coverage BCMSD, ranging from upper submicron particles sizes to larger than 1 µm, contributes to a substantial proportion of total BC mass and absorption. However, the current time resolution of larger-coverage BCMSD
measurement was limited to 1 d, which was insufficient to characterize
variation of larger-coverage BCMSD. In this study, a new method to determine equivalent BCMSD (eBCMSD) was proposed from size-resolved absorption coefficient measured by an aerodynamic aerosol classifier in tandem with an aethalometer. The proposed method could measure larger-coverage eBCMSD with a time resolution as high as 1 h and was validated by comparing the measurement results with refractory BCMSD (rBCMSD) measured by a differential mobility analyzer in tandem with a single-particle soot photometer (DMA–SP2) for particle sizes larger than 300 nm during a field measurement in the Yangtze River Delta. Bulk refractory BC mass concentration (mrBC,bulk) by DMA–SP2 was underestimated by 33 % compared to bulk equivalent BC mass concentration (meBC,bulk) by this method because of the limited size range of measurement for DMA–SP2. Uncertainty analysis of this method was performed with respect to mass absorption cross-section (MAC), transfer function inversion, number fraction of BC-containing particle and instrumental noise. The results indicated that MAC was the main uncertainty source, leading to meBC,bulk values that varied from −20 % to 28 %. With the advantage of a wide size coverage up to 1.5 µm, high time resolution, easy operation and low cost, this method is expected to have wide applications in field measurement for better estimating the radiative properties and climate effects of BC.


Na Ma

Papers

Digital image watermarking robust to geometric attacks based on wavelet domain

A stratified image-hiding method based on chaos

New method to determine black carbon mass size distribution