Search

"The use of ear information for people identification has been under testing at least for 100 years. However, it is still an open issue if the ears can be considered unique or unique enough to be used as biometric feature. In this paper a biometric system for human identification based on ear recognition is presented. The ear is modeled as a set of contours extracted from the ear image with an edge potential function. The matching algorithm has been tested in presence of several image modifications. Two human ear databases have been used for the tests. The experimental results show the effectiveness of the proposed scheme."

In this paper a methodology for digital image forgery detection by means of an unconventional use of image quality assessment is addressed. In particular, the presence of differences in quality degradations impairing the images is adopted to reveal the mixture of different source patches. The ratio behind this work is in the hypothesis that any image may be affected by artifacts, visible or not, caused by the processing steps: acquisition (i.e., lens distortion, acquisition sensors imperfections, analog to digital conversion, single sensor to color pattern interpolation), processing (i.e., quantization, storing, jpeg compression, sharpening, deblurring, enhancement), and rendering (i.e., image decoding, color/size adjustment). These defects are generally spatially localized and their strength strictly depends on the content. For these reasons they can be considered as a fingerprint of each digital image. The proposed approach relies on a combination of image quality assessment systems. The adopted no-reference metric does not require any information about the original image, thus allowing an efficient and stand-alone blind system for image forgery detection. The experimental results show the effectiveness of the proposed scheme.

In this paper we propose a new hybrid architecture between client/server and P2P network architectures in order to provide better service quality to the end-user. To distribute and protect the content, we use a discrete geometry tool as the Finite Radon Transform (FRT) in a Maximum Distance Separable (MDS) fashion. The presented results clarify the interest of the proposed architecture in terms of QoS.

'View plus depth' is an attractive compact representation format for 3D video compression and transmission. It combines 2D video with depth map sequence aligned in a per-pixel manner to represent the moving 3D scene in interest. Any different-perspective view can be synthesized out if this representation through Depth-Image Based Rendering (DIBR). However, such rendering is prone to disocclusion errors: regions originally covered by foreground objects become visible in the synthesized view and have to be filled with perceptually-meaningful data. In this work, a technique for reducing the perceived artifacts by inpainting the disoccluded areas is proposed. Based on Criminisi's exemplar-based inpainting algorithm, the developed technique recovers the disoccluded areas by using pixels of similar blocks surrounding it. In the original work, a moving window is centered on the boundaries between known and unknown parts ('target window'). The known pixels are used to select windows which are most similar to the target one. When this process is completed, the unknown region of the target patch is filled with a weighted combination of pixels from the selected windows. In the proposed scheme, the priority map, which defines the rule for selecting the order of pixels to be filled, has been modified to meet the requirement for disocclusion hole filling and a better non-local mean estimate has been suggested accordingly. Furthermore, the search for similar patches has also been extended to previous and following frames of the video under processing, thus improving both computational e±ciency and resulting quality. The effectiveness of the proposed method is demonstrated by objective and subjective tests.

The use of digital media for improving the effectiveness of teaching methodologies in Universities is increasing. In this contribution the experience performed at University of Roma TRE is presented. Since 2005 an online contest is used in the Multimedia class for improving both knowledge and human interaction. This paper shows the competitive-collaborative learning scheme adopted and it reports the feedback received by the students that has been collected by means of a questionnaire. The obtained comments show the effectiveness of the proposed learning scheme.

The increasing use of digital image-based applications is resulting in huge databases that are often difficult to use and prone to misuse and privacy concerns. These issues are especially crucial in medical applications. The most commonly adopted solution is the encryption of both the image and the patient data in separate files that are then linked. This practice results to be inefficient since, in order to retrieve patient data or analysis details, it is necessary to decrypt both files. In this contribution, an alternative solution for secure medical image annotation is presented. The proposed framework is based on the joint use of a key-dependent wavelet transform, the Integer Fibonacci-Haar transform, of a secure cryptographic scheme, and of a reversible watermarking scheme. The system allows: i) the insertion of the patient data into the encrypted image without requiring the knowledge of the original image, ii) the encryption of annotated images without causing loss in the embedded information, and iii) due to the complete reversibility of the process, it allows recovering the original image after the mark removal. Experimental results show the effectiveness of the proposed scheme.

In this paper a commutative watermarking and ciphering scheme for digital images is presented. The commutative property of the proposed method allows to cipher a watermarked image without interfering with the embedded signal or to watermark an encrypted image still allowing a perfect deciphering. Both operations are performed on a parametric transform domain: the Tree Structured Haar transform. The key dependence of the adopted transform domain increases the security of the overall system. In fact, without the knowledge of the generating key it is not possible to extract any useful information from the ciphered-watermarked image. Experimental results show the effectiveness of the proposed scheme.

In this contribution, an evaluation of the effectiveness of Application Layer-Forward Error Correction (AL-FEC) scheme in video communications over unreliable channels is presented. In literature, several AL-FEC techniques for reducing the effect of noisy transmission on multimedia communication have been adopted. Recently, their use has been proposed for inclusion in TV over IP broadcasting international standards. The objective of the analysis performed in this paper is to verify the effectiveness of AL-FEC techniques in terms of perceived Quality of Service (QoS) and more in general of Quality of Experience (QoE), and to evaluate the trade-off between AL-FEC redundancy and video quality degradation for a given packet loss ratio. To this goal, several channel error models are investigated (random i.i.d. losses, burst losses, and network congestions) on test sequences encoded at 2 and 4 Mbps. The perceived quality is evaluated by means of three quality metrics: the full-reference objective quality metric NTIA-VQM combined with the ITU-T Rec. G.1070, the full-reference DMOS-KPN metric, and the pixel-wise error comparison performed by using the PSNR distortion measure. A post-processing synchronization between the original and the reconstructed stream has also been designed for improving the fidelity of the performed quality measures. The experimental results show the effectiveness and the limits of the Application Layer protection schemes. © 2011 Battisti et al; licensee Springer.

"Low-cost personal computers, wireless access technologies, the Internet, and computer-equipped classrooms allow the design of novel and complementary methodologies for teaching digital information security in electrical engineering curricula. The challenges of the current digital information era require experts who are effectively able to counteract piracy, forgery, copyright infringement, and so on. Digital watermarking is one possible technique for fighting piracy, which consists of the insertion of invisible but robust information to protect the data. In this paper, a new teaching approach, designed for testing student skills and progressing in multimedia data protection, is presented. This consists of a distributed security game where students compete by first using the developed watermarking techniques and then attacking each other's methods, thus verifying their robustness. Groups of students from different universities and countries play against each other, trying to compromise other teams' hiding systems while protecting their own data from attacks. The proposed methodology can be considered as an appealing approach for stimulating learning, cooperation, and team competition. The effectiveness of the teaching method is verified by a student survey and their academic results."

Due to the recent success of 3D cinema, 3D video has been gathering considerable interest and delivery of 3D video to home TVs and mobile devices has been actively researched. A broadcast-friendly 3D video delivery format is so-called 'view plus depth', where single video sequence is augmented by dense depth information. Based on it, desired views can be synthesized at the receiver side. While well susceptible for effective compression, this representation presents problems related with occluded areas which become visible in the synthesized views. Different occlusion filling techniques have been developed varying in quality and complexity. This contribution aims at providing an objective and subjective comparison of three such techniques. These include adaptive pre-filtering of depth maps, and one simplified and one high-performance inpainting techniques. The latter two have been specifically modified for the case of occlusion filling. We have aimed especially at ranking the performance in the case of mobile 3D imaging. Along with objective comparisons, results from subjective tests are presented as well. Both groups of results demonstrate the superiority of the second inpainting technique, which is however also the most computationally expensive one.

In this contribution a novel reversible data hiding scheme for digital images is presented. The proposed technique allows the exact recovery of the original image upon extraction of the embedded information. Lossless recovery of the original is achieved by adopting the histogram shifting technique in a novel wavelet domain: the Integer Fibonacci-Haar Transform, which is based on a parameterized subband decomposition of the image. In particular, the parametrization depends on a selected Fibonacci sequence. The use of this transform increases the security of the proposed method. Experimental results show the effectiveness of the proposed scheme. © 2010 Copyright SPIE - The International Society for Optical Engineering.

In this contribution a novel method for video error control and concealment is proposed. The system is based on the use of data hiding techniques for transmitting the extra information needed to recover the data lost during transmission. The embedded data is a sub sampled binary version of each key frame of the shot. The embedding is performed by using the Quantization Index Modulation (QIM) scheme in the 3D wavelet transform domain. The experimental results show the effectiveness of the proposed approach. ©2010 IEEE.

In this paper a watermarking scheme based on the Human Visual System (HVS) is presented. A Quantization Index Modulation - Dither Modulation scheme is used in the Discrete Cosine Transform domain for the embedding. The watermark quantization step is selected according to the inter-frequency masking effect computed by using a HVS-inspired objective image quality metric. Experimental results demonstrate the effectiveness and the robustness of the proposed solution.

In this contribution the robustness of a novel steganographic scheme based on the generalized Fibonacci sequence against Chi-square attacks is investigated. In essence, an image is first represented in a basis defined by a generalized Fibonacci sequence. Then the secret data are inserted by substitution technique into selected bit planes preserving the first order distributions, and finally, the inverse Fibonacci decomposition is applied to obtain the stego-image. Secret data are scrambled before the embedding to improve the security of the whole system. In order to perform Chi-square attacks, the knowledge of both the parameters determining the binary Fibonacci representation of an image is assumed. Experimental results show that no visual impairments are introduced and the probability of detecting the presence of hidden data is small even if a modest capacity loss is present. © 2009 SPIE-IS&T.

In this paper, two new full-reference metrics for image quality assessment are presented. They are based on the Peak-Signal-to-Noise Ratio (PSNR) and Universal Quality Index (UQI) modified to take into account the Human Visual System (HVS) properties. Many studies confirm that the HVS is more sensitive to low frequency distortions rather than to high frequency ones. It is also very sensitive to contrast changes and noise. To test the effectiveness of the proposed metrics, we have performed a subjective experiment. In our experiment we have used seven types of distortions with three distortion levels in each. Three independent groups of observers from Finland, Ukraine and Italy, have been participating in image quality evaluation test. The analysis of the results shows that the proposed PSNR-HVS provides better correlation to Mean Observer Score (MOS) than PSNR, and that the proposed UQI-HVS metric outperforms two recently proposed state-of-the-art metrics: UQI and MSSIM.

A novel method for watermarking and ciphering color images, based on the joint use of a key-dependent wavelet transform with a secure cryptographic scheme, is presented. The system allows to watermark encrypted data without requiring the knowledge of the original data and also to cipher watermarked data without damaging the embedded signal. Since different areas of the proposed transform domain are used for encryption and watermarking, the extraction of the hidden information can be performed without deciphering the cover data and it is also possible to decipher watermarked data without removing the watermark. Experimental results show the effectiveness of the proposed scheme.

This paper proposes a novel data hiding scheme in which a payload is embedded into the discrete cosine transform domain. The characteristics of the Human Visual System (HVS) with respect to image fruition have been exploited to adapt the strength of the embedded data and integrated in the design of a digital image watermarking system. By using an HVS-inspired image quality metric, we study the relation between the amount of data that can be embedded and the resulting perceived quality. This study allows one to increase the robustness of the watermarked image without damaging the perceived quality, or, as alternative, to reduce the impairments produced by the watermarking process given a fixed embedding strength. Experimental results show the effectiveness and the robustness of the proposed solution.

In this paper a novel method for watermarking and ciphering color images is presented. The aim of the system is to allow the watermarking of encrypted data without requiring the knowledge of the original data. By using this method, it is also possible to cipher watermarked data without damaging the embedded signal. Furthermore, the extraction of the hidden information can be performed without deciphering the cover data and it is also possible to decipher watermarked data without removing the watermark. The transform domain adopted in this work is the Fibonacci-Haar wavelet transform. The experimental results show the effectiveness of the proposed scheme. © 2008 SPIE-IS&T.

This paper presents a novel spatial data hiding scheme based on the Least Significant Bit insertion. The bitplane decomposition is obtained by using the (p, r) Fibonacci sequences. This decomposition depends on two parameters, p and r. Those values increase the security of the whole system; without their knowledge it is not possible to perform the same decomposition used in the embedding process and to extract the embedded information. Experimental results show the effectiveness of the proposed method.

In this paper a joint watermarking and ciphering scheme for digital images is presented. Both operations are performed on a key-dependent transform domain. The commutative property of the proposed method allows to cipher a watermarked image without interfering with the embedded signal or to watermark an encrypted image still allowing a perfect deciphering. Furthermore, the key dependence of the transform domain increases the security of the overall system. Experimental results show the effectiveness of the proposed scheme.

In this contribution, a new image database for testing full-reference image quality assessment metrics is presented. It is based on 1700 test images (25 reference images, 17 types of distortions for each reference image, 4 levels for each type of distortion). Using this image database, 654 observers from three different countries (Finland, Italy, and Ukraine) have carried out about 400000 individual human quality judgments (more than 200 judgments for each distorted image). The obtained mean opinion scores for the considered images can be used for evaluating the performances of visual quality metrics as well as for comparison and for the design of new metrics. The database, with testing results, is freely available.

In this contribution, we present a novel technique for imperceptible and robust watermarking of digital images. It is based on the host image 2-th level decomposition using the Fibonacci-Haar Transform (FHT) and on the Singular Value Decomposition (SVD) of the transformed subbands. The main contributions of this approach are the use of the FHT for hiding purposes, the flexibility in data hiding capacity, and the key-dependent secrecy of the used transform. The experimental results show the effectiveness of the proposed approach both in perceived quality of the watermarked image and in robustness against the most common attacks.

In this paper, a novel data-hiding technique based on the Fibonacci representation of digital images is presented. A generalization of the classical Least Significant Bit (LSB) embedding method is performed. The Fibonacci representation of grey level images requires 12 bit planes instead of the usual 8 planes of binary representation. Experimental results show that, such a redundant scheme outperforms the classical LSB method resulting in marked images having less perceptual distortion even if different planes from the lowest bit plane are selected for embedding. The computational cost of the embedding scheme is compatible with the classical LSB data hiding scheme.

Reversible data hiding deals with the insertion of auxiliary information into a host data without causing any permanent degrada- tion to the original signal. In this contribution a high capacity reversible data hiding scheme, based on the classical difference expansion insertion algorithm, is presented. The method exploits a prediction stage, followed by prediction errors modification, both in the spatial domain and in the S-transform domain. Such two step embedding allows us to achieve high embedding capacity while preserving a high image quality, as demonstrated in the experimental results. © 2012 SPIE and IS&T. (DOI: 10.1117/1.JEI.21.3.033013)

In this paper a watermarking method based on the Haar wavelet transform is proposed. The hiding procedure is performed in the LL subband of the first level of Haar decomposition of the image. The coefficients resilient to specific attacks are modified in order to obtain a robust embedding scheme. The proposed method is used to define a mask to perform the embedding in the wavelet transform domain. As well known from literature, the transmitted data are subject to many different distortions. The aim of this work is to select the coefficients in the LL subband that are more robust to the most common types of distortions like gaussian noise, rotation, motion, blurring, JPEG and sharpening. Several tests have been carried out to verify the effectiveness of the proposed method.

Publication in the conference proceedings of EUSIPCO, Lisbon, Portugal, 2014