Localization of JPEG double compression through multi-domain convolutional neural networks

When an attacker wants to falsify an image, in most of cases she/he will perform a JPEG recompression. Different techniques have been developed based on diverse theoretical assumptions but very effective solutions have not been developed yet. Recently, machine learning based approaches have been started to appear in the field of image forensics to solve diverse tasks such as acquisition source identification and forgery detection. In this last case, the aim ahead would be to get a trained neural network able, given a to-be-checked image, to reliably localize the forged areas. With this in mind, our paper proposes a step forward in this direction by analyzing how a single or double JPEG compression can be revealed and localized using convolutional neural networks (CNNs). Different kinds of input to the CNN have been taken into consideration, and various experiments have been carried out trying also to evidence potential issues to be further investigated.Comment: Accepted to CVPRW 2017, Workshop on Media Forensic

Fasti dei sacerdoti del culto di Vulcano ad Ostia

Come è noto, il tratto distintivo del panorama religioso ostiense è costituito dal culto di Vulcano. Ciononostante, nella letteratura scientifica è stato trascurato l’importante contributo offerto dai frammenti dei Fasti dei sacerdoti minori del culto, aediles e praetores. Partendo da questi e riprendendo in esame le numerose iscrizioni che li riguardano si è cercato di ricostruire il tessuto sociale che li ha prodotti, individuando nell’età di Commodo un momento di svolta nel reclutamento. Tale svolta può essere interpretata come il riflesso di una maggiore ingerenza di Roma in un culto che, ai suoi massimi livelli, aveva il controllo su tutto le aree sacre della colonia.As we know, the most distinctive feature in the history of Ostia's religion is the pre-eminence of the cult of Vulcan. Nevertheless, in the scientific literature has been overlooked the important contribution offered by the fragments of the Fasti of minor cult priests, aediles and praetores. Starting from these and taking into consideration the numerous inscriptions which concern them we tried to reconstruct the social context that has produced them, identifying the age of Commodus a turning point in recruitment. This turning point can be interpreted as a reflection of greater Rome's interference in a cult that, at its highest levels, had control over the sacred areas of the colony

I protagonisti della scena tra immagine e testo

Questo contributo intende indagare se e in che modo per i protagonisti dello spettacolo dell’Occidente romano di età imperiale sia stato elaborato un sistema di segni, verbali e figurati, che fosse al tempo stesso individuante della professione praticata e capace di esprimere l’eccezionalità della prestazione, quale riconosciuta dal pubblico, non disgiunte da un’intenzione di durata. Come si potrà vedere, in realtà l’eccezionalità di tali personaggi trova un riflesso diretto assai limitato e comunque quasi esclusivamente in contesti non ufficiali, privati e sepolcrali, preferendo il testo, più spesso che l’immagine, per tramandare il ricordo della vittoria.This paper aims to investigate whether and how in the Western Roman empire the stage stars were identified by a system of verbal and iconic signs, both individualising their profession and capable of expressing the exceptionality of their performance — as recognized by the public —, not separated by an intention of being long-lasting. As a result, we will have to admit that the exceptionality of these stars had a very limited echo, almost exclusively in non-official contexts, private and burial. Text, more often than images, carried out the task of perpetuating the memory of victory

Memoria ed epigrafia. Il pauper a Roma nel I secolo d.C., un progetto in corso

Un progetto di ricerca portato avanti dalle due Autrici si propone di indagare le caratteristiche e le eventuali modifiche nelle pratiche funerarie epigrafiche della ‘classe media’ urbana nel primo secolo del Principato. Dopo aver chiarito il perché della cronologia indicata e chi s’intende indicare con la parola pauper, viene proposto un esempio dell’analisi in corso di realizzazione, concentrando l’attenzione su 14 epitaffi di individui del mondo dello spettacolo, selezionati in base a diversi criteri. Il commento comprende: l’impatto del monumento urbano in relazione ad altri edifici esistenti, il ritratto del defunto attraverso i dati biografici e altri elementi, il ruolo occupato nella società, il rapporto tra i vivi e i morti, attraverso l’utilizzo di epiteti specifici, il modo particolare in cui s’indicano le relazioni familiari, i divieti, le minacce, l’espressione della volontà testamentaria.A research project carried out by the two Authors aims to investigate the characteristics and possible changes in epigraphic funerary practices of ‘middle class’ of Rome in the first century of the imperial age. After clarifying the reasons for the chronology indicated and who is signified with the word ‘pauper’, here is an example of the analysis in progress, focusing on 14 epitaphs made for people from the entertainment world. The review includes: the impact of urban monument in relation to other existing buildings, a biographical portrait of the deceased, through biographical data and other factors, the role played in society, the relationship between the living and dead, through the use of specific epithets, the particular way in which family relationships have been indicated, prohibitions, threats, the expression of the will and testament

An Algorithm for Motion Parameter Direct Estimate

Motion estimation in image sequences is undoubtedly one of the most studied research fields, given that motion estimation is a basic tool for disparate applications, ranging from video coding to pattern recognition. In this paper a new methodology which, by minimizing a specific potential function, directly determines for each image pixel the motion parameters of the object the pixel belongs to is presented. The approach is based on Markov random fields modelling, acting on a first-order neighborhood of each point and on a simple motion model that accounts for rotations and translations. Experimental results both on synthetic (noiseless and noisy) and real world sequences have been carried out and they demonstrate the good performance of the adopted technique. Furthermore a quantitative and qualitative comparison with other well-known approaches has confirmed the goodness of the proposed methodology

Tracing images back to their social network of origin: A CNN-based approach

Recovering information about the history of a digital content, such as an image or a video, can be strategic to address an investigation from the early stages. Storage devices, smart-phones and PCs, belonging to a suspect, are usually confiscated as soon as a warrant is issued. Any multimedia content found is analyzed in depth, in order to trace back its provenance and, if possible, its original source. This is particularly important when dealing with social networks, where most of the user-generated photos and videos are uploaded and shared daily. Being able to discern if images are downloaded from a social network or directly captured by a digital camera, can be crucial in leading consecutive investigations. In this paper, we propose a novel method based on convolutional neural networks (CNN) to determine the image provenance, whether it originates from a social network, a messaging application or directly from a photo-camera. By considering only the visual content, the method works irrespective of an eventual manipulation of metadata performed by an attacker. We have tested the proposed technique on three publicly available datasets of images downloaded from seven popular social networks, obtaining state-of-the-art results

Bibbie atlantiche e non solo nella biblioteca della cattedrale di Messina in epoca normanna

Studying the old Cathedral Library of Messina, whose holdings today are preserved mostly in Madrid (BNE), we have focused on the presence of one “Atlantic” Bible and some non-biblical manuscripts with a similar size to the Bibles. The production of these books can be located in Central Italy, perhaps in Rome, since they share features of this region. They mostly transmit biblical commentaries or patristic writings (Augustine, Gregory the Great). Three hypotheses will be pursued on the inclusion of this manuscripts in the holdings of the Cathedral Library: the commission by someone from the cathedral staff (as for the manuscripts of the diocese of Troia, commissioned by Bishop William); the purchase by the clerics of the cathedral for liturgical needs; the gift by one or more clerics who had arrived in Sicily with his own books. Two more hypotheses will be explored on the size of these books: the intent to declare the intellectual and political dependency of at least one part of the diocese of Messina on papal power as opposed to the other political forces; the need of books for liturgical and ecclesiastical uses. In the latter case, the presence of manuscripts of this size might be explaned as a preference for another type of book production other than that of Southern Italy: Norman readers do not seem to have a taste for Southern Italian books in Beneventana script

Counter-forensics of SIFT-based copy-move detection by means of keypoint classification

Copy-move forgeries are very common image manipulations that are often carried out with malicious intents. Among the techniques devised by the 'Image Forensic' community, those relying on scale invariant feature transform (SIFT) features are the most effective ones. In this paper, we approach the copy-move scenario from the perspective of an attacker whose goal is to remove such features. The attacks conceived so far against SIFT-based forensic techniques implicitly assume that all SIFT keypoints have similar properties. On the contrary, we base our attacking strategy on the observation that it is possible to classify them in different typologies. Also, one may devise attacks tailored to each specific SIFT class, thus improving the performance in terms of removal rate and visual quality. To validate our ideas, we propose to use a SIFT classification scheme based on the gray scale histogram of the neighborhood of SIFT keypoints. Once the classification is performed, we then attack the different classes by means of class-specific methods. Our experiments lead to three interesting results: (1) there is a significant advantage in using SIFT classification, (2) the classification-based attack is robust against different SIFT implementations, and (3) we are able to impair a state-of-the-art SIFT-based copy-move detector in realistic cases

Sull’iscrizione di Adriano I

Sebbene l’iscrizione di Adriano I sia forse una delle iscrizioni medievali più studiate e più citate, essa continua ad essere un unicum nell’ambito della produzione epigrafica europea di fine VIII secolo. L’a., dopo aver attuato un confronto compiuto con le altre testimonianze epigrafiche coeve, prova ad avanzare l’ipotesi che l’iscrizione oggi murata sulla facciata del portico di San Pietro, sia in realtà un rifacimento, dovuto al deterioramento della lastra, collocabile nella Roma di metà ‘400. La nuova ipotesi, espressa con molta cautela, mira comunque principalmente a ribadire che l’iscrizione di Adriano I non può essere in ogni caso assunta come prototipo della rinascita della capitale di età imperiale in epoca carolingia.Pope Adrian I’s inscription, now visible on the front of the portico of St. Peter’s, despite being one of the most studied medieval epigraphs, continues to be an unicum within the European engraved production of the end of the 8th century. This article offers an accurate comparison of it with other contemporary inscriptions and advances the hypothesis that it could be a remake, datable to the middle of the 15th century in Rome and due to the deterioration of the original plate. The new hypothesis, very cautious, mainly aims at confirming that Adrian I’s inscription cannot be assumed as a prototype of the revival of the Roman square capitals in the Carolingian ag

Bibbie atlantiche e non solo nella biblioteca della cattedrale di Messina in epoca normanna

Studying the old Cathedral Library of Messina, whose holdings are today preserved mostly in Madrid (BNE), we have focused on the presence of at least two “Atlantic” Bibles and some non-biblical manuscripts with a format similar to that of the Bibles. The production of these books can be located in Central Italy, perhaps in Rome, since they share features of this region. They transmit mostly biblical commentaries or patristic writings, such as those of Augustine and Gregory the Great. Why were these manuscripts included in the holdings of the Cathedral Library and when? Three hypotheses will be pursued. First, someone from the cathedral staff could have commissioned them, as was the case for the manuscripts of the diocese of Troia, commissioned by Bishop William. Second, the manuscripts could have been bought by the clerics of the cathedral for liturgical needs; third, the manuscripts could have been left as gifts by a donor (one or more clerics) who had arrived in Sicily with his own books. Why was this format chosen for these books? Two hypotheses will be explored. First, the intent to declare the intellectual and political dependency of at least one part of the diocese of Messina on papal power as opposed to other political forces. Or, second, the need to provide books for liturgical and ecclesiastical uses, drawing from the books available in the Norman kingdom or in other lands. In the latter case, the presence of manuscripts with this format might be explained as a preference for book production other than that of Southern Italy, because it seems Norman readers did not have a taste for Southern Italian books in the Beneventana script