Can feature information interaction help for information fusion in multimedia problems?

This article presents the information-theoretic based feature information interaction, a measure that can describe complex feature dependencies in multivariate settings. According to the theoretical development, feature interactions are more accurate than current, bivariate dependence measures due to their stable and unambiguous definition. In experiments with artificial and real data we compare first the empirical dependency estimates of correlation, mutual information and 3-way feature interaction. Then, we present feature selection and classification experiments that show superior performance of interactions over bivariate dependence measures for the artificial data, for real world data this goal is not achieved ye

Annotation de vidéos par paires rares de concepts

National audienceLa détection d'un concept visuel dans les vidéos est une tâche difficile, spécialement pour les concepts rares ou pour ceux dont il est compliqué de décrire visuellement. Cette question devient encore plus difficile quand on veut détecter une paire de concepts au lieu d'un seul. En effet, plus le nombre de concepts présents dans une scène vidéo est grand, plus cette dernière est complexe visuellement, et donc la difficulté de lui trouver une description spécifique s'accroit encore plus. Deux directions principales peuvent eˆtre suivies pour tacler ce problème: 1) détecter chaque concept séparément et combiner ensuite les prédictions de leurs détecteurs correspondants d'une manière similaire à celle utilisée souvent en recherche d'information, ou 2) considérer le couple comme un nouveau concept et générer un classifieur supervisé pour ce nouveau concept en inférant de nouvelles annotations à partir de celles des deux concepts formant la paire. Chacune de ces approches a ses avantages et ses inconvénients. Le problème majeur de la deuxième méthode est la nécessité d'un ensemble de données annotées, surtout pour la classe positive. S'il y a des concepts rares, cette rareté s'accroit encore plus pour les paires formées de leurs combinaisons. D'une autre part, il peut y avoir deux concepts assez fréquents mais il est très rare qu'ils occurrent conjointement dans un meˆme document. Certains travaux de l'état de l'art ont proposé de palier ce problème en récoltant des exemples représentatifs des classes étudiées du web, mais cette tâche reste couˆteuse en temps et argent. Nous avons comparé les deux types d'approches sans recourir à des ressources externes. Notre évaluation a été réalisée dans le cadre de la sous-tâche "détection de paire de concepts" de la tâche d'indexation sémantique (SIN) de TRECVID 2013, et les résultats ont révélé que pour le cas des vidéos, si on n'utilise pas de ressources d'information externes, les approches qui fusionnent les résultats des deux détecteurs sont plus performantes, contrairement à ce qui a été montré dans des travaux antérieurs pour le cas des images fixes. La performance des méthodes décrites dépasse celle du meilleur résultat officiel de la campagne d'évaluation précédemment citée, de 9% en termes de gain relatif sur la précision moyenne (MAP)

Properties of optimally weighted data fusion in CBMIR

Content-Based Multimedia Information Retrieval (CBMIR) systems which leverage multiple retrieval experts (En ) of- ten employ a weighting scheme when combining expert re- sults through data fusion. Typically however a query will comprise multiple query images (Im ) leading to potentially N × M weights to be assigned. Because of the large number of potential weights, existing approaches impose a hierarchy for data fusion, such as uniformly combining query image results from a single retrieval expert into a single list and then weighting the results of each expert. In this paper we will demonstrate that this approach is sub-optimal and leads to the poor state of CBMIR performance in benchmarking evaluations. We utilize an optimization method known as Coordinate Ascent to discover the optimal set of weights (|En | · |Im |) which demonstrates a dramatic difference be- tween known results and the theoretical maximum. We find that imposing common combinatorial hierarchies for data fu- sion will half the optimal performance that can be achieved. By examining the optimal weight sets at the topic level, we observe that approximately 15% of the weights (from set |En | · |Im |) for any given query, are assigned 70%-82% of the total weight mass for that topic. Furthermore we discover that the ideal distribution of weights follows a log-normal distribution. We find that we can achieve up to 88% of the performance of fully optimized query using just these 15% of the weights. Our investigation was conducted on TRECVID evaluations 2003 to 2007 inclusive and ImageCLEFPhoto 2007, totalling 181 search topics optimized over a combined collection size of 661,213 images and 1,594 topic images

Simulating the Future of Concept-Based Video Retrieval under Improved Detector Performance

In this paper we address the following important questions for concept-based video retrieval: (1) What is the impact of detector performance on the performance of concept-based retrieval engines, and (2) will these engines be applicable to real-life search tasks if detector performance improves in the future? We use Monte Carlo simulations to answer these questions. To generate the simulation input, we propose to use a probabilistic model of two Gaussians for the confidence scores that concept detectors emit. Modifying the model's parameters affects the detector performance and the search performance. We study the relation between these two performances on two video collections. For detectors with similar discriminative power and a concept vocabulary of around 100 concepts, the simulation reveals that in order to achieve a search performance of 0.20 mean average precision (MAP) -- which is considered sufficient performance for real-life applications -- one needs detectors with at least 0.60 MAP. We also find that, given our simulation model and low detector performance, MAP is not always a good evaluation measure for concept detectors since it is not strongly correlated with the search performance

Video Content Understanding Using Text

The rise of the social media and video streaming industry provided us a plethora of videos and their corresponding descriptive information in the form of concepts (words) and textual video captions. Due to the mass amount of available videos and the textual data, today is the best time ever to study the Computer Vision and Machine Learning problems related to videos and text. In this dissertation, we tackle multiple problems associated with the joint understanding of videos and text. We first address the task of multi-concept video retrieval, where the input is a set of words as concepts, and the output is a ranked list of full-length videos. This approach deals with multi-concept input and prolonged length of videos by incorporating multi-latent variables to tie the information within each shot (short clip of a full-video) and across shots. Secondly, we address the problem of video question answering, in which, the task is to answer a question, in the form of Fill-In-the-Blank (FIB), given a video. Answering a question is a task of retrieving a word from a dictionary (all possible words suitable for an answer) based on the input question and video. Following the FIB problem, we introduce a new problem, called Visual Text Correction (VTC), i.e., detecting and replacing an inaccurate word in the textual description of a video. We propose a deep network that can simultaneously detect an inaccuracy in a sentence while benefiting 1D-CNNs/LSTMs to encode short/long term dependencies, and fix it by replacing the inaccurate word(s). Finally, as the last part of the dissertation, we propose to tackle the problem of video generation using user input natural language sentences. Our proposed video generation method constructs two distributions out of the input text, corresponding to the first and last frames latent representations. We generate high-fidelity videos by interpolating latent representations and a sequence of CNN based up-pooling blocks

A Fusion-Based Framework for Wireless Multimedia Sensor Networks in Surveillance Applications

Multimedia sensors enable monitoring applications to obtain more accurate and detailed information. However, the development of efficient and lightweight solutions for managing data traffic over wireless multimedia sensor networks (WMSNs) has become vital because of the excessive volume of data produced by multimedia sensors. As part of this motivation, this paper proposes a fusion-based WMSN framework that reduces the amount of data to be transmitted over the network by intra-node processing. This framework explores three main issues: 1) the design of a wireless multimedia sensor (WMS) node to detect objects using machine learning techniques; 2) a method for increasing the accuracy while reducing the amount of information transmitted by the WMS nodes to the base station, and; 3) a new cluster-based routing algorithm for the WMSNs that consumes less power than the currently used algorithms. In this context, a WMS node is designed and implemented using commercially available components. In order to reduce the amount of information to be transmitted to the base station and thereby extend the lifetime of a WMSN, a method for detecting and classifying objects on three different layers has been developed. A new energy-efficient cluster-based routing algorithm is developed to transfer the collected information/data to the sink. The proposed framework and the cluster-based routing algorithm are applied to our WMS nodes and tested experimentally. The results of the experiments clearly demonstrate the feasibility of the proposed WMSN architecture in the real-world surveillance applications

Semantic concept detection from visual content with statistical learning

Master'sMASTER OF SCIENC

Use Case Oriented Medical Visual Information Retrieval & System Evaluation

Large amounts of medical visual data are produced daily in hospitals, while new imaging techniques continue to emerge. In addition, many images are made available continuously via publications in the scientific literature and can also be valuable for clinical routine, research and education. Information retrieval systems are useful tools to provide access to the biomedical literature and fulfil the information needs of medical professionals. The tools developed in this thesis can potentially help clinicians make decisions about difficult diagnoses via a case-based retrieval system based on a use case associated with a specific evaluation task. This system retrieves articles from the biomedical literature when querying with a case description and attached images. This thesis proposes a multimodal approach for medical case-based retrieval with focus on the integration of visual information connected to text. Furthermore, the ImageCLEFmed evaluation campaign was organised during this thesis promoting medical retrieval system evaluation

combining multimodal external resources for event-based news video retrieval and question answering

Ph.DDOCTOR OF PHILOSOPH

Vereinheitlichte Anfrageverarbeitung in heterogenen und verteilten Multimediadatenbanken

Multimedia retrieval is an essential part of today's world. This situation is observable in industrial domains, e.g., medical imaging, as well as in the private sector, visible by activities in manifold Social Media platforms. This trend led to the creation of a huge environment of multimedia information retrieval services offering multimedia resources for almost any user requests. Indeed, the encompassed data is in general retrievable by (proprietary) APIs and query languages, but unfortunately a unified access is not given due to arising interoperability issues between those services. In this regard, this thesis focuses on two application scenarios, namely a medical retrieval system supporting a radiologist's workflow, as well as an interoperable image retrieval service interconnecting diverse data silos. The scientific contribution of this dissertation is split in three different parts: the first part of this thesis improves the metadata interoperability issue. Here, major contributions to a community-driven, international standardization have been proposed leading to the specification of an API and ontology to enable a unified annotation and retrieval of media resources. The second part issues a metasearch engine especially designed for unified retrieval in distributed and heterogeneous multimedia retrieval environments. This metasearch engine is capable of being operated in a federated as well as autonomous manner inside the aforementioned application scenarios. The remaining third part ensures an efficient retrieval due to the integration of optimization techniques for multimedia retrieval in the overall query execution process of the metasearch engine.Egal ob im industriellen Bereich oder auch im Social Media - multimediale Daten nehmen eine immer zentralere Rolle ein. Aus diesem fortlaufendem Entwicklungsprozess entwickelten sich umfangreiche Informationssysteme, die Daten für zahlreiche Bedürfnisse anbieten. Allerdings ist ein einheitlicher Zugriff auf jene verteilte und heterogene Landschaft von Informationssystemen in der Praxis nicht gewährleistet. Und dies, obwohl die Datenbestände meist über Schnittstellen abrufbar sind. Im Detail widmet sich diese Arbeit mit der Bearbeitung zweier Anwendungsszenarien. Erstens, einem medizinischen System zur Diagnoseunterstützung und zweitens einer interoperablen, verteilten Bildersuche. Der wissenschaftliche Teil der vorliegenden Dissertation gliedert sich in drei Teile: Teil eins befasst sich mit dem Problem der Interoperabilität zwischen verschiedenen Metadatenformaten. In diesem Bereich wurden maßgebliche Beiträge für ein internationales Standardisierungsverfahren entwickelt. Ziel war es, einer Ontologie, sowie einer Programmierschnittstelle einen vereinheitlichten Zugriff auf multimediale Informationen zu ermöglichen. In Teil zwei wird eine externe Metasuchmaschine vorgestellt, die eine einheitliche Anfrageverarbeitung in heterogenen und verteilten Multimediadatenbanken ermöglicht. In den Anwendungsszenarien wird zum einen auf eine föderative, als auch autonome Anfrageverarbeitung eingegangen. Abschließend werden in Teil drei Techniken zur Optimierung von verteilten multimedialen Anfragen präsentiert