1,720,993 research outputs found
Image Watermarking Robust Against Non-Linear Value-Metric Scaling Attacks Based on Higher Order Statistics
No full textA new QIM-based image watermarking system for still images is proposed. The new system is expressly designed to cope with non-linear value-metric scaling attacks such as histogram stretching and gamma correction. By recognizing that any value-metric scaling attack must not change the global appearance of the image, we argue that the watermark should be inserted into high level visual features. We move a first step into this direction by proposing a system embedding the watermark into the kurtosis of selected image blocks. Though the kurtosis is not strictly invariant against non-linear gain, its value tends to remain constant whenever the image content is not altered significantly. The experiments we carried out confirm the validity of the new system, though some problems still need to be solved to make it suitable for real applications
A New Video authentication Template Based on Bubble random Sampling
No full textThe rapid growth of digital video distribution has highlighted new important issues in digital rights management, as well as in other important applications such as video authentication. Digital watermarking offers a promising solution against piracy and it is therefore a very active area of research. However, robustness to video manipulations, either malicious or not, is a demanding task because there are many different types of possible attacks that can be envisioned. Among these, geometric and temporal distortions play the major roles. The countermeasures against these specific attacks are still an open challenge. In this paper we propose the use of a video authentication template based on bubble random sampling. The authentication template is introduced in order to ensure temporal synchronization
and to prevent content tampering. The simulation results are encouraging and this approach is therefore worth further development efforts
High Dynamic Range Image Watermarking
No full textHigh Dynamic Range (HDR) images represent the future format for digital images since they allow more sen- sitive rendering. However, nowadays special types of pre- processing collectively known as tone mapping operators are needed to adapt HDR images to currently existing displays. Tone mapped images, although of reduced dynamic range, have nonetheless high quality and hence retain some commercial value. In this paper we propose a solution to the problem of HDR watermarking, e.g. for copyright embedding, that should survive tone mapping. Therefore, the requirements imposed on the watermark encompass imperceptibility, a cer- tain degree of security and robustness to tone mapping operators. The proposed watermarking system belongs to the blind, detectable category, it is based on the QIM paradigm and employs a higher order statistic as feature. Preliminary experimental analysis shows positive results; more work is needed and currently underway
A proposal for Video Signature Tool and Video Fingerprinting
No full textIn this document we present and evaluate a video signature system, proposed by Signals and Communications Laboratory – Department of Electronic for Automation, University of Brescia (Italy). The proposed Video Signature is MPEG-7 compliant. The technology is based on the use of many different features (color, motion, etc.). The preliminary studies show that these features have relevant characteristics in their development in time. The testing results prove that the features act differently with respect of the type and modification the query suffered
Variable-size Symmetry-based Graph Fourier Transforms for Image Compression
No full textModern compression systems use linear transformations in their encoding and decoding processes, with transforms providing compact signal representations. While multiple data-dependent transforms for image/video coding can adapt to diverse statistical characteristics, assembling large datasets to learn each transform is challenging. Also, the resulting transforms typically lack fast implementation, leading to significant computational costs. Thus, despite many papers proposing new transform families, the most recent compression standards predominantly use traditional separable sinusoidal transforms. This paper proposes integrating a new family of Symmetry-based Graph Fourier Transforms (SBGFTs) of variable sizes into a coding framework, focusing on the extension from our previously introduced 8x8 SBGFTs to the general case of NxN grids. SBGFTs are non-separable transforms that achieve sparse signal representation while maintaining low computational complexity thanks to their symmetry properties. Their design is based on our proposed algorithm, which generates symmetric graphs on the grid by adding specific symmetrical connections between nodes and does not require any data-dependent adaptation. Furthermore, for video intra-frame coding, we exploit the correlations between optimal graphs and prediction modes to reduce the cardinality of the transform sets, thus proposing a low-complexity framework. Experiments show that SBGFTs outperform the primary transforms integrated in the explicit Multiple Transform Selection (MTS) used in the latest VVC intra-coding, providing a bit rate saving percentage of 6.23%, with only a marginal increase in average complexity. A MATLAB implementation of the proposed algorithm is available online at [1]
High Dynamic Range Image Watermarking Robust Against Tone-Mapping Operators
No full textHigh dynamic range (HDR) images represent the future format for digital images since they allow accurate rendering of a wider range of luminance values. However, today special types of preprocessing, collectively known as tone-mapping (TM) operators, are needed to adapt HDR images to currently existing displays. Tone-mapped images, although of reduced dynamic range, have nonetheless high quality and hence retain some commercial value. In this paper, we propose a solution to the problem of HDR image watermarking, e.g., for copyright embedding, that should survive TM. Therefore, the requirements imposed on the watermark encompass imperceptibility, a certain degree of security, and robustness to TM operators. The proposed watermarking system belongs to the blind, detectable category; it is based on the quantization index modulation (QIM) paradigm and employs higher order statistics as a feature. Experimental analysis shows positive results and demonstrates the system effectiveness with current state-of-art TM algorithms
Improved Face Tracking Thanks to Local Features Correspondence
No full textIn this paper, we propose a technique to enhance the quality of detected face tracks in videos. In particular, we present a tracking algorithm that can improve the temporal localization of the tracks, remedying to the unavoidable failures of the face detection algorithms. Local features are extracted and tracked to “fill the gaps” left by missed detections. The principal aim of this work is to provide robust and well localized tracks of faces to a system of Interactive Movietelling, but the concepts can be extended whenever there is the necessity to localize the presence of a determined face even in environments where the face detection is, for any reason, difficult. We test the effectiveness of the proposed algorithm in terms of faces localization both in space and time, first assessing the performance in an ad-hoc simulation scenario and then showing output examples of some real-world video sequences
Effective Image Fingerprint Extraction Based on Random Bubble Sampling
No full textIn this paper we propose an algorithm for image fingerprint extraction based on random selection of circular bubbles on the considered image. In more detail, a fingerprint vector is associated to the image, the components of which are the variances of pixel luminance values in randomly selected circular zones of the image. The positions and radius of these bubbles result from a random selection, whose parameters are user-defined. The obtained fingerprint has then been used for content-based image retrieval, using the standard euclidean distance as similarity metric between the extracted features. Experiments based on the detection of various linearly and nonlinearly distorted versions of a test image in a large database show very promising results
Evaluation of Core Experiment for MPEG-7 Video Signature Tool
No full textThe present document evaluates and discusses the experiment conditions proposed in the VCE-7 CE on Video Signature, discussed in the previous MPEG meetings [MPEG-VS-09-01] [MPEG-VS-09-02]. In particular we present some simulation results that show the weaknesses of the evaluation procedure, proposed in the VCE-7 CE on Video Signature, and that highlight some aspects that could impair the performance evaluation of the here considered technology in a realistic environment. Therefore, we propose a new Core Experiment which will consider this issues
Identification versus CBCD: a comparison of different evaluation techniques
No full textFingerprint techniques have a significant advantage in respect of watermarking: a fingerprint can be extracted in each moment of the lifetime of a multimedia content. This aspect is fundamental to solve the problem of copy detection mainly because many copies can be available in huge amount of data in circulation and because each copy can be attacked in several ways (compression, re-encoding, text-overlay, etc.). In this paper the problem of copy detection is studied and tested from two different point of views: content based and identification approaches. The results show that the proposed system is quite robust to some copy modifications and most of all show that the overall results depend on the evaluation method used for testing
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