Catálogo de publicaciones - libros

As most previous wavelet analysis based 3-D mesh watermarking methods embed the watermark information into wavelet coefficients arranged in a certain order, they have not been used as blind schemes since the connectivity information must be exactly known in the watermark extraction process. In this paper, we propose a blind watermarking method based on wavelet analysis for 3-D mesh model. Two new techniques are introduced. One is to exploit the statistical features of scale coefficients on an approximation (low resolution) level for watermark embedding. Another is to extract the hidden watermark, not from the same resolution level as used in embedding process, but directly from the spatial domain. As the proposed watermark detection does not require the wavelet analysis, any pre-processing such as registration and re-sampling, is not needed. These techniques allow to detect the watermark without referring to the original meshes. In addition, the proposed are applicable directly to irregular meshes by using irregular wavelet analysis. Through simulations, we prove that our method is fairly robust against various attacks including topological ones.

This paper presents a novel watermarking scheme for 3D keyframe animation based on geometric structure and interpolator. The geometric watermarking embeds the watermark into the distribution of vertex coordinates in each of initial mesh models. The interpolator watermarking embeds the same watermark into key values in position interpolator. Experimental results show that the proposed scheme has the robustness against various geometric attacks and timeline attacks as well as the invisibility.

A robust video watermarking scheme via temporal segmentation and middle frequency component adaptive modification is presented. First, the video clip is sliced into a shot sequence by temporal video segmentation. Then, several consecutive shots are selected from the shot sequence to makeup a video segment with proper duration. The watermark is embedded into the video segment by equally dividing it into many units, and modifying the middle frequency component of frames in each unit. In addition, the scheme adjusts the modification strength of every coefficient adaptively according to the change between consecutive frames and Watson’s DCT based visual model. Experimental results show that the scheme is resilient to many kinds of temporal desynchronization, spatial desynchronization and photometric distortion at the same time.

One of the main goals of watermarking is to optimize capacity while preserving high video fidelity. This paper describes a watermarking scheme based on the spread spectrum paradigm with capacity enhancement using a state-of-the-art error correction technique – duo-binary turbo coding. A new watermark composition with novel bit-wise watermark bits interleaving scheme and bit-rate control on the macro-block level is proposed. In previous works, the perceptual watermark adjustment was mainly based on Watson Just Noticeable Difference (JND) model. A new JND estimation model based on block classification is presented. In addition, experimental results on perceptibility and robustness to transcoding are reported.

Image splicing is a commonly used technique in image tampering. This paper presents a novel approach to passive detection of image splicing. In the proposed scheme, the image splicing detection problem is tackled as a twoclass classification problem under the pattern recognition framework. Considering the high non-linearity and non-stationarity nature of image splicing operation, a recently developed Hilbert-Huang transform (HHT) is utilized to generate features for classification. Furthermore, a well established statistical natural image model based on moments of characteristic functions with wavelet decomposition is employed to distinguish the spliced images from the authentic images. We use support vector machine (SVM) as the classifier. The initial experimental results demonstrate that the proposed scheme outperforms the prior arts.

In this paper, we propose a new encryption method for intellectual property rights management of MPEG-4 coder. DCT coefficients and motion vectors (MVs) are used for the combination encryption of the MPEG-4 video. Experimental results indicate that the proposed joint and partial encryption technique provides levels of security and achieves a simple and coding-efficient architecture with no adverse impact on error resilience.

This paper presents a data hiding technique based on a new compression enhancement called Film Grain Technology. Film grain is a mid-frequency noise-like pattern naturally appearing in imagery captured on film. The Film Grain Technology is a method for modeling and removing the film grain, thus enhancing the compression efficiency, and then using the model parameters to create synthetic film grain at the decoder. We propose slight modifications to the decoder that enable the synthetic film grain to represent metadata available at the decoder. We examine a number of implementation approaches and report results of fidelity and robustness experiments.

Since digital right management of digital media data has received considerable attention recently, protection of halftone image documents becomes another important topic. Image-based visual cryptography is found to provide an alternative for applications of copyright protection by overlapping more than one secret embedded image to show the hidden information. In this paper, we propose a novel screening halftoning-based visual cryptography method for halftone image protection. Compared with the existing methods, the major contributions of our method contain (i) improved quality of the halftone images and extracted secrets; (ii) unlimited database size of protected halftone images; (iii) more than two halftone images can be overlapped to show the hidden secret; (iv) only one conjugate screen pair in our method is able to achieve the maximum clarity of extracted secrets in random screening. Experimental results and comparisons with a state of the art method demonstrate the effectiveness of our method.

Extensive testing shows that the audio Zernike moments in lower orders are very robust to common signal processing operations, such as MP3 compression, low-pass filtering, etc. Based on the observations, in this paper, a robust watermark scheme is proposed by embedding the bits into the low-order moments. By analyzing and deducting the linear relationship between the audio amplitude and moments, watermarking the low-order moments is achieved in time domain by scaling sample values directly. Thus, the degradation in audio reconstruction from a limited number of watermarked Zernike moments is avoided. Experimental works show that the proposed algorithm achieves strong robustness performance due to the superiorities of exploited low-order moments.

The quantization-based watermarking schemes such as QIM or SCS are known to be very vulnerable to the amplitude modification attack. The amplitude modification attack results in the change of quantization step size so the estimation of a modified quantization step size is required before watermark detection. In this paper, we analyze the quantization error function of the audio signal having any shape of probability density function, and analytically determine the search interval that minimizes the quantization error considering both detection performance and computational complexity. It is shown that the appropriate search interval can be determined from the frame-based mean and variance of the input signal without regard to its shape of probability density function. Experimental results for real audio data verify that the derived search interval provides the accurate estimation of the modified quantization step size under amplitude modification attack.