Information extraction from printed documents is still a crucial problem in many interorganizational workflows. Solutions for other application domains, for example, the web, do not fit this peculiar scenario well, as printed documents do not carry any explicit structural or syntactical description. Moreover, printed documents usually lack any explicit indication about their source. We present a system, which we call PATO, for extracting predefined items from printed documents in a dynamic multisource scenario. PATO selects the source-specific wrapper required by each document, determines whether no suitable wrapper exists, and generates one when necessary. PATO assumes that the need for new source-specific wrappers is a part of normal system operation: new wrappers are generated online based on a few point-and-click operations performed by a human operator on a GUI. The role of operators is an integral part of the design and PATO may be configured to accommodate a broad range of automation levels. We show that PATO exhibits very good performance on a challenging data set composed of more than 600 printed documents drawn from three different application domains: invoices, datasheets of electronic components, and patents. We also perform an extensive analysis of the crucial tradeoff between accuracy and automation level.

Electronic devices capable of wireless communication are becoming ubiquitous. They enable a wide range of novel applications but these are often difficult to deploy in practice because wireless channels provide ample opportunities to attackers. A number of approaches have been proposed for building secure channels in these scenarios. An approach that would be simple, general and effective consists in establishing a shared secret between two devices by placing them in physical contact for a few seconds. This approach has not been exploited in practice due to the lack of common interfaces. We demonstrate the practical feasibility of the approach for devices equipped with a small LCD screen and cameras. We transfer secret keys between Android-based smartphones put in contact with each other for just a few seconds. The transfer occurs across a visual channel that cannot be intercepted.

We consider the automatic annotation of faces of people mentioned in news. News stories provide a constant flow of potentially useful image indexing information, due to their huge diffusion on the web and to the involvement of human operators in selecting relevant images for the stories. In this work we investigate the possibility of actually exploiting this wealth of information. We propose and evaluate a system for automatic face annotation of image news that is fully unsupervised and does not require any prior knowledge about topic or people involved. Key feature of our proposal is that it attempts to identify the essential piece of information -- how a person with a given name looks like -- by querying popular image search engines. Mining the web allows overcoming intrinsic limitations of approaches built above a predefined collection of stories: our system can potentially annotate people never handled before since its knowledge base is constantly expanded, as long as search engines keep on indexing the web. On the other hand, leveraging on image search engines forces to cope with the substantial amount of noise in search engine results. Our contribution shows experimentally that automatic face annotation may indeed be achieved based entirely on knowledge that lives in the web.

A key step in the understanding of printed documents is their classification based on the nature of information they contain and their layout. In this work we consider a dynamic scenario in which document classes are not known a priori and new classes can appear at any time. This open world setting is both realistic and highly challenging. We use an SVM-based classifier based only on image-level features and use a nearest-neighbor approach for detecting new classes. We assess our proposal on a real-world dataset composed of 562 invoices belonging to 68 different classes. These documents were digitalized after being handled by a corporate environment, thus they are quite noisy---e.g., big stamps and handwritten signatures at unfortunate positions and alike. The experimental results are highly promising.

Web site defacement, the process of introducing unauthorized modifications to a Web site, is a very common form of attack. In this paper we describe and evaluate experimentally a framework that may constitute the basis for a defacement detection service capable of monitoring thousands of remote Web sites systematically and automatically. In our framework an organization may join the service by simply providing the URLs of the resources to be monitored along with the contact point of an administrator. The monitored organization may thus take advantage of the service with just a few mouse clicks, without installing any software locally or changing its own daily operational processes. Our approach is based on anomaly detection and allows monitoring the integrity of many remote Web resources automatically while remaining fully decoupled from them, in particular, without requiring any prior knowledge about those resources. We evaluated our approach over a selection of dynamic resources and a set of publicly available defacements. The results are very satisfactory: all attacks are detected while keeping false positives to a minimum. We also assessed performance and scalability of our proposal and we found that it may indeed constitute the basis for actually deploying the proposed service on a large scale.

Hand-held devices have become widespread and provided with significant computing capabilities, which results in an increasing pressure for using these devices to perform tasks formerly limited to notebooks, like web browsing. Due to their small screens, however, hand-held devices cannot visualize directly documents that were not designed explicitly for small-screen rendering. Such documents may be rendered either at a scale too small to be useful, or at a scale that requires intensive scrolling operations by the user. Unfortunately, scrolling a small window across a large document with a hand-held device is quite cumbersome. In this paper we propose a scrolling system much simpler and more natural to use, based on the embedded camera-a component available in every modern hand-held device. We detect device motion by analyzing the video stream generated by the camera and then we transform the motion in a scrolling of the content rendered on the screen. This way, the user experiences the device screen like a small movable window on a larger virtual view, without requiring any dedicated motion-detection hardware. We performed an experimental evaluation aimed at assessing the effectiveness of the proposed system in the considered scenario, characterized by low image quality, unpredictable framed scene and soon. We performed an objective benchmark quantifying the accuracy of the detected trajectory and a subjective benchmark examining users' confidence with the proposed system. For the latter evaluation, we involved a panel of 20 subjects that executed a trajectory with our system and, as a comparison, with keyboard, mouse and touchpad. The results demonstrate that our approach is indeed practical.