Pan-pan Niu

A robust blind color image watermarking in quaternion Fourier transform domain

Highlights? To embed the digital watermark in quaternion Fourier transform domain, which improves the robustness against color attacks. ? To correct the watermarked image by LS-SVM classification, which improve the robustness against geometrical distortions. ? To modify the symmetric quaternion Fourier transform coefficients, which improve the watermark imperceptibility. Most of the existing color image watermarking schemes were designed to mark the image luminance component only, which have some disadvantages: (i) they are sensitive to color attacks because of ignoring the correlation between different color channels, (ii) they are always not robust to geometric distortions for neglecting the watermark desynchronization. It is a challenging work to design a robust color image watermarking scheme. Based on quaternion Fourier transform and least squares support vector machine (LS-SVM), we propose a robust blind color image watermarking in quaternion Fourier transform domain, which has good visual quality. Firstly, the original color image is divided into color image blocks. Then, the fast quaternion Fourier transform is performed on the color image block. Finally, the digital watermark is embedded into original color image by adaptively modulating the real quaternion Fourier transform coefficients of color image block. For watermark decoding, the LS-SVM correction with pseudo-Zernike moments is utilized. Experimental results show that the proposed color image watermarking is not only robust against common image processing operations such as filtering, JPEG compression, histogram equalization, and image blurring, but also robust against the geometrical distortions.

A robust digital audio watermarking based on statistics characteristics

In digital audio watermarking, the watermarks vulnerability to desynchronization attacks has long been a difficult problem. According to the audio statistics characteristics and synchronization code technique, a new robust audio watermarking scheme against desynchronization attacks is proposed in this paper. Firstly, the original digital audio is segmented and then each audio segment is cut into two parts. Secondly, with the spatial watermarking technique, the synchronization code is embedded into the statistics average value of audio samples in the first part. Finally, the second part of audio segment is cut into audio sections, the DWT is performed on the audio sections, and the watermark bit is embedded into the statistics average value of low frequency components. Experimental results show that the proposed scheme is inaudible and robust against common signals processing, including MP3 compression, low-pass filtering, noise addition, and equalization, etc. Moreover, it also survives several desynchronization attacks, such as random cropping, amplitude variation, pitch shifting, time-scale modification, and jittering, etc.

A new robust color image watermarking using local quaternion exponent moments

Abstract Desynchronization attacks that cause displacement between embedding and detection are usually difficult for watermark to survive. It is a challenging work to design a robust image watermarking scheme against desynchronization attacks, especially for color host images. In this paper, we propose a robust color image watermarking scheme based on local quaternion exponent moments. The proposed scheme has the following advantages: (1) the stable and uniform color image feature points are extracted by the new color image detector, in which the probability density gradient and color invariance model are used, (2) the affine invariant local feature regions are constructed adaptively according to the variation of local probability density and (3) the effective quaternion exponent moments are derived and introduced to embed watermark in the color image, which consider the correlation between different color channels. Experiments are carried out on a color image set of 100 images collected from Internet, and the preliminary results show that the proposed color image watermarking is not only invisible and robust against common image processing operations such as sharpening, noise adding, and JPEG compression, but also robust against the desynchronization attacks.

Image denoising using nonsubsampled shearlet transform and twin support vector machines

Denoising of images is one of the most basic tasks of image processing. It is a challenging work to design a edge/texture-preserving image denoising scheme. Nonsubsampled shearlet transform (NSST) is an effective multi-scale and multi-direction analysis method, it not only can exactly compute the shearlet coefficients based on a multiresolution analysis, but also can provide nearly optimal approximation for a piecewise smooth function. Based on NSST, a new edge/texture-preserving image denoising using twin support vector machines (TSVMs) is proposed in this paper. Firstly, the noisy image is decomposed into different subbands of frequency and orientation responses using the NSST. Secondly, the feature vector for a pixel in a noisy image is formed by the spatial geometric regularity in NSST domain, and the TSVMs model is obtained by training. Then the NSST detail coefficients are divided into information-related coefficients and noise-related ones by TSVMs training model. Finally, the detail subbands of NSST coefficients are denoised by using the adaptive threshold. Extensive experimental results demonstrate that our method can obtain better performances in terms of both subjective and objective evaluations than those state-of-the-art denoising techniques. Especially, the proposed method can preserve edges and textures very well while removing noise.

A Robust, Digital-Audio Watermarking Method

Most of the previous audio-watermarking schemes are robust to common signal-processing attacks, but show severe problems when faced with desynchronization attacks. To solve the problems associated with these approaches, we propose an audio-watermarking scheme based on support-vector-machine (SVM) theory to protect against desynchronization attacks by using audio statistics characteristics and a synchronization code technique. Experimental results with SVM show that our proposed scheme is inaudible, robust against common signal processing, and robust against desynchronization attacks.

Robust image watermarking approach using polar harmonic transforms based geometric correction

Geometric distortions that cause displacement between embedding and detection are usually difficult for watermark to survive. It is a challenging work to design a robust image watermarking scheme against geometric distortions. In this paper, we propose a robust image watermarking approach using Polar Harmonic Transforms (PHTs) based geometric correction. The novelty of our approach is that (1) the optimal Nonsubsampled Shearlet Transform (NSST), which can provide nearly optimal approximation for 2D image function, is used to embed digital watermark, and (2) the PHTs are exploited for estimating the geometric distortions parameters in order to permit watermark extraction. Experimental results show that the proposed approach not only provides better imperceptibility and robustness against various attacks (including common image processing operations and geometric distortions), but also yields better watermark detection performance than some state-of-the-art image watermarking schemes.

Robust Color Image Watermarking Using Geometric Invariant Quaternion Polar Harmonic Transform

It is a challenging work to design a robust color image watermarking scheme against geometric distortions. Moments and moment invariants have become a powerful tool in robust image watermarking owing to their image description capability and geometric invariance property. However, the existing moment-based watermarking schemes were mainly designed for gray images but not for color images, and detection quality and robustness will be lowered when watermark is directly embedded into the luminance component or three color channels of color images. Furthermore, the imperceptibility of the embedded watermark is not well guaranteed. Based on algebra of quaternions and polar harmonic transform (PHT), we introduced the quaternion polar harmonic transform (QPHT) for invariant color image watermarking in this article, which can be seen as the generalization of PHT for gray-level images. It is shown that the QPHT can be obtained from the PHT of each color channel. We derived and analyzed the rotation, scaling, and translation (RST) invariant property of QPHT. We also discussed the problem of color image watermarking using QPHT. Experimental results are provided to illustrate the efficiency of the proposed color image watermarking against geometric distortions and common image processing operations (including color attacks).

A robust content based audio watermarking using UDWT and invariant histogram

Desynchronization attack is known as one of the most difficult attacks to resist, for it can desynchronize the location of the watermark and hence causes incorrect watermark detection. It is a challenging work to design a robust audio watermarking scheme against desynchronization attacks. Based on undecimated discrete wavelet transform (UDWT) and invariant histogram, we propose a new content based audio watermarking algorithm with good audible quality and reasonable resistance toward desynchronization attacks in this paper. Firstly, the undecimated discrete wavelet transform (UDWT) is performed on original host audio. Secondly, the invariant histogram is extracted from a selected wavelet coefficients range in the low frequency subband. Then, the bin of histogram is divided into many groups, each group including four consecutive bins. For each group, one watermark bit is embedded by reassigning the number of wavelet coefficients in this group of four bins. Finally, the digital watermark is embedded into the original audio signal in UDWT domain by modifying a small set of wavelet coefficients. Simulation results show that the proposed watermarking scheme is not only inaudible and robust against common signal processing operations such as MP3 compression, noise addition, and low-pass filtering etc, but also robust against the desynchronization attacks such as random cropping, time-scale modification, pitch shifting, and jittering etc.

Affine invariant image watermarking using intensity probability density-based Harris Laplace detector

Feature point based image watermarking against geometric distortions has attracted great attention in recent years. However, for the state-of-the-art intensity based feature points detectors, the feature points often gather at textured portions of the image or on the edges where the change of intensity is significant, so that many feature points capture the same portion of the image, which makes the watermark be vulnerable to local geometric distortions. In this paper, we propose an affine invariant image watermarking scheme with good visual quality and reasonable resistance toward local geometric distortions, which utilizes the intensity probability density-based Harris-Laplace detector. Firstly, the uniform and robust feature points are extracted by utilizing modified Harris-Laplace detector, in which the intensity probability density gradient is used instead of intensity gradient. Then, the affine invariant local ellipse regions (LERs) are constructed adaptively according to the variation of local intensity probability density. Finally, the digital watermark is embedded into the affine invariant LERs in nonsubsampled contourlet transform (NSCT) domain by modulating the lowpass NSCT coefficients. By binding the watermark with the affine invariant LERs, the watermark detection can be done without synchronization error. Experimental results show that the proposed image watermarking is not only invisible and robust against common image processing operations such as sharpening, noise adding, and JPEG compression, but also robust against the global affine transforms and local geometric distortions.

A new robust digital watermarking using local polar harmonic transform

The PHT modulus distribution for image Barbara under various attacks: (a) Gaussian filtering, (b) JPEG compression 50, (c) rotation, (d) scaling.Display Omitted The stable and uniform image feature points are extracted by the improved SURF detector.The affine invariant local feature regions are constructed adaptively.A new and effective 2D transform is introduced to embed watermark in the digital image. Geometric distortions are more difficult to tackle than other types of attacks. It is a challenging work to design a robust image watermarking scheme against geometric distortions. In this paper, we propose a robust digital image watermarking scheme based on local polar harmonic transform. The proposed scheme has the following advantages: (1) the stable and uniform image feature points are extracted by the improved speeded-up robust feature (SURF) detector, in which the probability density gradient is utilized, (2) the affine invariant local feature regions are constructed adaptively according to the variation of local probability density, and (3) a new and effective 2D transform, named polar harmonic transform (PHT), is introduced to embed watermark in the digital image. Experiments are carried out on a digital image set of 100 images collected from Internet, and the preliminary results show that the proposed image watermarking is not only invisible and robust against common image processing operations such as filtering, noise adding, and JPEG compression, but also robust against the geometric distortions.