Publications by Rita Cucchiara

In this paper we detail a proposal of exploitation of expert-made commentaries in a unified system for illuminated manuscripts images analysis. In particular we will explore the possibility to improve the automatic segmentation of meaningful pictures, as well as the retrieval by similarity search engine, using clusters of keywords extracted from commentaries as semantic information.

The term mobile is now added to most of computer based systems as synonymous of several different concepts, ranging on ubiquitousness, wireless connection, portability, and so on. In a similar manner, also the name mobile video surveillance is spreading, even though it is often misinterpreted with just limited views of it, such as front-end mobile monitoring, wireless video streaming, moving cameras, distributed systems. This chapter presents an overview of mobile video surveillance systems, focusing in particular on architectural aspects (sensors, functional units and sink modules). A short survey of the state of the art is presented. The chapter will also tackle some problems of video streaming and video tracking specifically designed and optimized for mobile video surveillance systems, giving an idea of the best results that can be achieved in these two foundation layers. © 2010 Springer-Verlag.

Dangerous situations arise in everyday life and many efforts have been lavished to exploit technology to increase the level of safety in urban areas. Video analysis is absolutely one of the most important and emerging technology for security purposes. Automatic video surveillance systems commonly analyze the scene searching for moving objects. Well known techniques exist to cope with this problem that is commonly referred as change detection". Every time a dierence against a reference model is sensed, it should be analyzed to allow the system to discriminateamong a usual situation or a possible threat. When the sensor is a camera, motion is the key element to detect changes and moving objects must be correctly classied according to their nature. In this context we can distinguish among two dierent kinds of threat that can lead to dangerous situations in a video-surveilled environment. The first one is due to environmental changes such as rain, fog or smoke present in the scene. This kind of phenomena are sensed by the camera as moving pixelsand, subsequently as moving objects in the scene. This kind of threats shares some common characteristics such as texture, shape and color information and can be detected observing the features' evolution in time. The second situation arises whenpeople are directly responsible of the dangerous situation. In this case a subject is acting in an unusual way leading to an abnormal situation. From the sensor's point of view, moving pixels are still observed, but specic features and time-dependent statistical models should be adopted to learn and then correctly detect unusual and dangerous behaviors. With these premises, this chapter will present two different case studies. The rst one describes the detection of environmental changes in theobserved scene and details the problem of reliably detecting smoke in outdoor environments using both motion information and global image features, such as color information and texture energy computed by the means of the Wavelet transform.The second refers to the problem of detecting suspicious or abnormal people behaviors by means of people trajectory analysis in a multiple cameras video-surveillance scenario. Specically, a technique to infer and learn the concept of normality is proposed jointly with a suitable statistical tool to model and robustly compare people trajectories.

Many works address the problem of object detection by means of machine learning with boosted classifiers. They exploit sliding window search, spanning the whole image: the patches, at all possible positions and sizes, are sent to the classifier. Several methods have been proposed to speed up the search (adding complementary features or using specialized hardware). In this paper we propose a statisticalbased search approach for object detection which uses a Monte Carlo sampling approach for estimating the likelihood density function with Gaussian kernels. The estimation relies on a multi-stage strategy where the proposal distribution is progressively refined by taking into account the feedback of the classifier (i.e. its response). For videos, this approach is plugged in a Bayesian-recursive framework which exploits the temporal coherency of the pedestrians. Several tests on both still images and videos on common datasets are provided in order to demonstrate therelevant speedup and the increased localization accuracy with respect to sliding window strategy using a pedestrian classifier based on covariance descriptors and a cascade of Logitboost classifiers.

Achieving both localization and identication of people ina wide open area using only cameras can be a challengingtask, which requires cross-cutting requirements : high reso-lution for identication, whereas low resolution for having awide coverage of the localization. Consequently, this paperproposes the joint use of cameras (only devoted to local-ization) and RFID sensors (devoted to identication) withthe nal objective of detecting and localizing intruders. Toground the observations on a common coordinate system,a calibration procedure is dened. This procedure only de-mands a training phase with a single person moving in thescene holding a RFID tag. Although preliminary, the resultsdemonstrate that this calibration is sufficiently accurate tobe applied whenever dierent scenarios, where area of over-lap between the eld of view (FoV) of a camera and theField of sense" (FoS) of a (blind) sensor must be efficientlydetermined.

In this paper we define a new paradigm for 8-connection labeling, which employes a general approach to improve neighborhood exploration and minimizes the number of memory accesses. Firstly we exploit and extend the decision table formalism introducing OR-decision tables, in which multiple alternative actions are managed. An automatic procedure to synthesize the optimal decision tree from the decision table is used, providing the most effective conditions evaluation order. Secondly we propose a new scanning technique that moves on a 2x2 pixel grid over the image, which is optimized by the automatically generated decision tree.An extensive comparison with the state of art approaches is proposed, both on synthetic and real datasets. The synthetic dataset is composed of different sizes and densities random images, while the real datasets are an artistic image analysis dataset, a document analysis dataset for text detection and recognition, and finally a standard resolution dataset for picture segmentation tasks. The algorithm provides an impressive speedup over the state of the art algorithms.

People social interaction analysis is a complex and interesting problem that can be faced from several points of view depending on the application context. In videosurveillance contexts many indicators of people habits and relations exist and, among these, people trajectories analysis can reveal many aspects of the way people behave in social environments. We propose a statistical framework for trajectories mining that analyzes, in an integrated solution, several aspects of the trajectories such as location, shape and speed properties. Three different models are proposed to deal with non-idealities of the selected features in conjunction with a robust inexact- matching similarity measure for comparing sequences with different lengths. Experimental results in a real scenario demonstrates the efficacy of the framework in clustering people trajectories with the purpose of analyze frequent behaviors in complex environments.

Contextual information can be used both to reduce computationsand to increase accuracy and this paper presentshow it can be exploited for people surveillance in terms ofperspective (i.e. weak scene calibration) and appearance ofthe objects of interest (i.e. relevance feedback on the trainingof a classifier). These techniques are applied to a pedestriandetector that exploits covariance descriptors througha LogitBoost classifier on Riemannian manifolds. The approachhas been tested on a construction working site wherecomplexity and dynamics are very high, making human detectiona real challenge. The experimental results demonstratethe improvements achieved by the proposed approach.

The use of polar representation of covariance descriptors, suitable for the classification of circular feature sets, is proposed. It overcomes the implicit limits of state-of-the-art methods based on axis-oriented rectangular patches. The suitability of the proposed solution is verified on two case studies, namely head detection and polymer classification in photomicrograph contexts.

This paper describes an interactive application for the exploration and annotation of illuminated manuscripts, which typically contain thousands of pictures, used to comment or embellish the manuscript Gothic text. The system is composed by a modern user interface for browsing, surfing and querying, an automatic segmentation module, to ease the initial picture extraction task, and a similarity based retrieval engine, used to provide visually assisted tagging capabilities. A relevance feedback procedure is included to further refine the results.