Publications

In this work, we describe in detail the MPEG-7 Shape Spectrum Descriptor and provide a set of tests with different 3D objects databases. To verify if the literature reported low performance of this descriptor were due to the comparison employed, we also used the Earth Movers Distance which allows much more detailed histograms comparisons. Finally we compare our outcomes with the best results in related work.

In this paper a practical color calibration procedure for dermatoscopic image acquisition is illustrated, with details on the algorithms employed and results on real data.

This paper describes a system for motion detection based on background suppression,specifically conceived for working in complex scenes with vacillating background,camouflage, illumination changing, etc.. The system contains proper techniques for background bootstrapping, shadow removal, ghost suppression and selective updating of the background model. The results on the challenging videos provided in VSSN '06 Open Source Algorithm Competition dataset demonstrate that the proposed system outperforms the widely-used mixture-of-Gaussians approach.

In semantic video adaptation measures of performance must consider the impact of the errors in the automatic annotation over the adaptation in relationship with the preferences and expectations of the user. In this paper, we define two new performance measures Viewing Quality Loss and Bit-rate Cost Increase, that are obtained from classical peak signal-to-noise ration (PSNR) and bit rate, and relate the results of semantic adaptation to the errors in the annotation of events and objects and the user's preferences and expectations. We present and discuss results obtained with a system that performs automatic annotation of soccer sport video highlights and applies different coding strategies to different parts of the video according to their relative importance for the end user. With reference to this framework, we analyze how highlights' statistics and the errors of the annotation engine influence the performance of semantic adaptation and reflect into the quality of the video displayed at the user's client and the increase of transmission costs.

This paper addresses multimedia tools for universal multimedia access to sports videos by means of automatic annotation and content-based adaptation. The goal is to provide boosting technologies to allow the new generations of mobile devices (phones and PDAs) to better exploit the available bandwidth and to achieve a reasonable cost/quality trade-off in remote access to long-lasting live events, such as sport competitions. Although the available bandwidth for mobile communication has increased thanks to new telecommunication standards such as GPRSand UMTS, it is still insufficient for high quality video transmission. The limited resources of low-cost terminals and the high costs of data transfer hinder de-facto many possible multimedia services. First, the quality is limited by the small display size and memory available on many mobile devices. Second, the limited bandwidthmay affect user satisfaction either because of the time spent waiting for the download or the latency in streaming a live video. Moreover, even if the user is willing to wait for the download or accepts frame dropping, a reduction of data to send would be unavoidable in order to bring down the costs of the service. As a matter of fact, most telecommunication companies charge a fee proportional to the number of bytes transferred. Hence, the cost of accessing a long-lasting live video, such as a 90-minute soccer competition, is stilltoo high for most users.

It is with considerable pride that we present this special issue of ACM multimedia based on the presentations at the third Video Surveillance and Sensor Network workshop, in conjunction with the ACM conference in Singapore 2005. The papers were thoroughly reviewed independently of the review process for the workshop. This special issue consists of eight papers drawn from a number of areas. It appears that we are breaking new ground as explained in this issue.Whenever we say multimedia, we think of systems and services that manage heterogeneous data for human-oriented applications; human users are normally the subjects who access and use multimedia data, multimediastreams, multimedia content, and multimedia interfaces in many different applications contexts. Following this abstraction, multimedia surveillance systems would be only a surveillance system able to produce output of the task in a multimedia format, providing distilled video, images and sounds of the monitored environment, which would possibly be annotated in an efficient and standard way or possibly transcoded in another media such as text or animation, to improve further querying to surveillance stored data.

In this paper, we propose a system for automatic video summarization at sub-shot level. Our work covers two main aspects: the first is the sub-shot detection, which is performed without a priori constraints on the number or length of the shots. The algorithm is based on color histograms and motion features, and employs fuzzy c-means with variable number of clusters. The second aspect is an in depth discussion on the annotation of summaries with the MPEG-7 standard. Results on mixed genres TV material, from TRECVID videos, are reported.

Logging information on moving objects is crucial in video surveillance systems. Distributed multi-camera systems can provide the appearance of objects/people from differentviewpoints and at different resolutions, allowing a more complete and precise logging of the information. This is achieved through consistent labeling to correlate collected information of the same person. This paper proposes a novel approach to consistent labeling also capable tofully characterize groups of people and to manage miss segmentations. The ground-plane homography and the epipolar geometry are automatically learned and exploited to warp objects’ principal axes between overlapped cameras. A MAP estimator that exploits two contributions (forward and backward) is used to choose the most probable label con£guration to be assigned at the handoff of a new object. Extensive experiments demonstrate the accuracy of the proposed method in detecting single and simultaneous handoffs, miss segmentations, and groups.

What approach or combination of approaches did you test in each of your submitted runs?TRECVID2005_UNIMORE_??.xml: the same linear transition detector (LTD) was tested forevery run, with ten uniformly spaced thresholds for the detection.What if any significant differences (in terms of what measures) did you find among theruns?The system behaved as expected: the higher the threshold the better the recall. Of course theprecision lowered correspondently. Interesting enough, it seems that we cannot overcome theoverall limit around 80% for recall and 88% for precision, independently of the other parameter.Based on the results, can you estimate the relative contribution of each component of yoursystem/approach to its effectiveness?One of the main objective of our system was to test the performance of a single algorithm forboth cuts and gradual transitions. So all the merit and the demerits are related to our LTD.Overall, what did you learn about runs/approaches and the research question(s) thatmotivated them?The use of a single algorithm allows the system to be run without training. Just a singleparameter may be employed to tune the sensibility of the system, thus allowing its use in generalpurpose/user friendly systems.