Image category recognition is important to access visual information on the level of objects and scene types. So far, intensity-based descriptors have been widely used for feature extraction at salient points. To increase illumination invariance and discriminative power, color descriptors have been proposed. Because many different descriptors exist, a structured overview is required of color invariant descriptors in the context of image category recognition. Therefore, this paper studies the invariance properties and the distinctiveness of color descriptors in a structured way. The analytical invariance properties of color descriptors are explored, using a taxonomy based on invariance properties with respect to photometric transformations, and tested experimentally using a dataset with known illumination conditions. In addition, the distinctiveness of color descriptors is assessed experimentally using two benchmarks, one from the image domain and one from the video domain. From the theoretical and experimental results, it can be derived that invariance to light intensity changes and light color changes affects category recognition. The results reveal further that, for light intensity changes, the usefulness of invariance is category-specific. Overall, when choosing a single descriptor and no prior knowledge about the dataset and object and scene categories is available, the OpponentSIFT is recommended. Furthermore, a combined set of color descriptors outperforms intensity-based SIFT and improves category recognition by 8% on the PASCAL VOC 2007 and by 7% on the MediaMill Challenge.
The Microsoft SenseCam is a small lightweight wearable camera used to passively capture photos and other sensor readings from a user’s day-to-day activities. It captures on average 3,000 images in a typical day, equating to almost 1 million images per year. It can be used to aid memory by creating a personal multimedia lifelog, or visual recording of the wearer’s life. However the sheer volume of image data captured within a visual lifelog creates a number of challenges, particularly for locating relevant content. Within this work, we explore the applicability of semantic concept detection, a method often used within video retrieval, on the domain of visual lifelogs. Our concept detector models the correspondence between low-level visual features and high-level semantic concepts (such as indoors, outdoors, people, buildings, etc.) using supervised machine learning. By doing so it determines the probability of a concept’s presence. We apply detection of 27 everyday semantic concepts on a lifelog collection composed of 257,518 SenseCam images from 5 users. The results were evaluated on a subset of 95,907 images, to determine the accuracy for detection of each semantic concept. We conducted further analysis on the temporal consistency, co-occurance and relationships within the detected concepts to more extensively investigate the robustness of the detectors within this domain.
Progress in visual-concept search suggests that machine understanding of images is within reach.
In the face of current large-scale video libraries, the practical applicability of content-based indexing algorithms is constrained by their efficiency. This paper strives for efficient large-scale video indexing by comparing various visual-based concept categorization techniques. In visual categorization, the popular codebook model has shown excellent categorization performance. The codebook model represents continuous visual features by discrete prototypes predefined in a vocabulary. The vocabulary size has a major impact on categorization efficiency, where a more compact vocabulary is more efficient. However, smaller vocabularies typically score lower on classification performance than larger vocabularies. This paper compares four approaches to achieve a compact codebook vocabulary while retaining categorization performance. For these four methods, we investigate the trade-off between codebook compactness and categorization performance. We evaluate the methods on more than 200 h of challenging video data with as many as 101 semantic concepts. The results allow us to create a taxonomy of the four methods based on their efficiency and categorization performance.
Social image analysis and retrieval is important for helping people organize and access the increasing amount of user-tagged multimedia. Since user tagging is known to be uncontrolled, ambiguous, and overly personalized, a fundamental problem is how to interpret the relevance of a user-contributed tag with respect to the visual content the tag is describing. Intuitively, if different persons label visually similar images using the same tags, these tags are likely to reflect objective aspects of the visual content. Starting from this intuition, we propose in this paper a neighbor voting algorithm which accurately and efficiently learns tag relevance by accumulating votes from visual neighbors. Under a set of well defined and realistic assumptions, we prove that our algorithm is a good tag relevance measurement for both image ranking and tag ranking. Three experiments on 3.5 million Flickr photos demonstrate the general applicability of our algorithm in both social image retrieval and image tag suggestion. Our tag relevance learning algorithm substantially improves upon baselines for all the experiments. The results suggest that the proposed algorithm is promising for real-world applications.
In this paper, we review 300 references on video retrieval, indicating when text-only solutions are unsatisfactory and showing the promising alternatives which are in majority concept-based. Therefore, central to our discussion is the notion of a semantic concept: an objective linguistic description of an observable entity. Specifically, we present our view on how its automated detection, selection under uncertainty, and interactive usage might solve the major scientific problem for video retrieval: the semantic gap. To bridge the gap, we lay down the anatomy of a concept-based video search engine. We present a component-wise decomposition of such an interdisciplinary multimedia system, covering influences from information retrieval, computer vision, machine learning, and human-computer interaction. For each of the components we review state-of-the-art solutions in the literature, each having different characteristics and merits. Because of these differences, we cannot understand the progress in video retrieval without serious evaluation efforts such as carried out in the NIST TRECVID benchmark. We discuss its data, tasks, results, and the many derived community initiatives in creating annotations and baselines for repeatable experiments. We conclude with our perspective on future challenges and opportunities.
Image collections are getting larger and larger. To access those collections, systems for managing, searching, and browsing are necessary. Visualization plays an essential role in such systems. Existing visualization systems do not analyze all the problems occurring when dealing with large visual collections. In this paper, we make these problems explicit. From there, we establish three general requirements: overview, visibility, and structure preservation. Solutions for each requirement are proposed, as well as functions balancing the different requirements. We present an optimal visualization scheme, supporting users in interacting with large image collections. Experimental results with a collection of 10,000 Corel images, using simulated user actions, show that the proposed scheme significantly improves performance for a given task compared to the 2D grid-based visualizations commonly used in content-based image retrieval.
Video search is an experience for the senses. As a result, traditional information retrieval metrics can't fully measure the quality of a video search system. To provide a more interactive assessment of today's video search engines, the authors have organized the VideOlympics as a real-time evaluation showcase where systems compete to answer specific video searches in front of a live audience. At VideOlympics, seeing and hearing is believing.
At one end of the spectrum, research in interactive content-based retrieval concentrates on machine learning methods for effective use of relevance feedback. On the other end, the information visualization community focuses on effective methods for conveying information to the user. What is lacking is research considering the information visualization and interactive retrieval as truly integrated parts of one content-based search system. In such an integrated system, there are many degrees of freedom like the similarity function, the number of images to display, the image size, different visualization modes, and possible feedback modes. To base the optimal values for all of those on user studies is unfeasible. We therefore develop search scenarios in which tasks and user actions are simulated. From there, the proposed scheme is optimized based on objective constraints and evaluation criteria. In such a manner, the degrees of freedom are reduced and the remaining degrees can be evaluated in user studies. In this article, we present a system that integrates advanced similarity based visualization with active learning. We have performed extensive experimentation on interactive category search with different image collections. The results using the proposed simulation scheme show that indeed the use of advanced visualization and active learning pays off in all of these datasets.
In this paper, we argue to learn dissimilarity for interactive search in content based image retrieval. In literature, dissimilarity is often learned via the feature space by feature selection, feature weighting or by adjusting the parameters of a function of the features. Other than existing techniques, we use feedback to adjust the dissimilarity space independent of feature space. This has the great advantage that it manipulates dissimilarity directly. To create a dissimilarity space, we use the method proposed by Pekalska and Duin, selecting a set of images called prototypes and computing distances to those prototypes for all images in the collection. After the user gives feedback, we apply active learning with a one-class support vector machine to decide the movement of images such that relevant images stay close together while irrelevant ones are pushed away (the work of Guo ). The dissimilarity space is then adjusted accordingly. Results on a Corel dataset of 10000 images and a TrecVid collection of 43907 keyframes show that our proposed approach is not only intuitive, it also significantly improves the retrieval performance.
In this paper, we propose an automatic video retrieval method based on high-level concept detectors. Research in video analysis has reached the point where over 100 concept detectors can be learned in a generic fashion, albeit with mixed performance. Such a set of detectors is very small still compared to ontologies aiming to capture the full vocabulary a user has. We aim to throw a bridge between the two fields by building a multimedia thesaurus, i.e., a set of machine learned concept detectors that is enriched with semantic descriptions and semantic structure obtained from WordNet. Given a multimodal user query, we identify three strategies to select a relevant detector from this thesaurus, namely: text matching, ontology querying, and semantic visual querying. We evaluate the methods against the automatic search task of the TRECVID 2005 video retrieval benchmark, using a news video archive of 85 h in combination with a thesaurus of 363 machine learned concept detectors. We assess the influence of thesaurus size on video search performance, evaluate and compare the multimodal selection strategies for concept detectors, and finally discuss their combined potential using oracle fusion. The set of queries in the TRECVID 2005 corpus is too small for us to be definite in our conclusions, but the results suggest promising new lines of research.
The six papers in this special section focus on semantic image and video indexing in broad domains. To bring semantics to the user in broad domains both the indexing and retrieval step have to be considered. The papers here address both steps and the relation to ontologies.
Effective video retrieval is the result of an interplay between interactive query selection, advanced visualization of results, and a goal-oriented human user. Traditional interactive video retrieval approaches emphasize paradigms, such as query-by-keyword and query-by-example, to aid the user in the search for relevant footage. However, recent results in automatic indexing indicate that query-by-concept is becoming a viable resource for interactive retrieval also. We propose in this paper a new video retrieval paradigm. The core of the paradigm is formed by first detecting a large lexicon of semantic concepts. From there, we combine query-by-concept, query-by-example, query-by-keyword, and user interaction into the MediaMill semantic video search engine. To measure the impact of increasing lexicon size on interactive video retrieval performance, we performed two experiments against the 2004 and 2005 NIST TRECVID benchmarks, using lexicons containing 32 and 101 concepts respectively. The results suggest that from all factors that play a role in interactive retrieval, a large lexicon of semantic concepts matters most. Indeed, by exploiting large lexicons, many video search questions are solvable without using query-by-keyword and query-by-example. What is more, we show that the lexicon-driven search engine outperforms all state-of-the-art video retrieval systems in both TRECVID 2004 and 2005.
As the world uses more digital video that requires greater storage space, Grid computing is becoming indispensable for urgent problems in multimedia content analysis. Parallel-Horus, a support tool for applications in multimedia Grid computing, lets users implement multimedia applications as sequential programs for efficient execution on clusters and Grids, based on wide-area multimedia services.
This paper presents the semantic pathfinder architecture for generic indexing of multimedia archives. The semantic pathfinder extracts semantic concepts from video by exploring different paths through three consecutive analysis steps, which we derive from the observation that produced video is the result of an authoring-driven process. We exploit this authoring metaphor for machine-driven understanding. The pathfinder starts with the content analysis step. In this analysis step, we follow a data-driven approach of indexing semantics. The style analysis step is the second analysis step. Here we tackle the indexing problem by viewing a video from the perspective of production. Finally, in the context analysis step, we view semantics in context. The virtue of the semantic pathfinder is its ability to learn the best path of analysis steps on a per-concept basis. To show the generality of this novel indexing approach we develop detectors for a lexicon of 32 concepts and we evaluate the semantic pathfinder against the 2004 NIST TRECVID video retrieval benchmark, using a news archive of 64 hours. Top ranking performance in the semantic concept detection task indicates the merit of the semantic pathfinder for generic indexing of multimedia archives.
We propose a generic and robust framework for news video indexing, which we found on a broadcast news production model. We identify within this model four production phases, each providing useful metadata for annotation. In contrast to semi-automatic indexing approaches, which exploit this information at production time, we adhere to an automatic data-driven approach. To that end, we analyze a digital news video using a separate set of multimodal detectors for each production phase. By combining the resulting production-derived features into a statistical classifier ensemble, the framework facilitates robust classification of several rich semantic concepts in news video; rich meaning that concepts share many similarities in their production process. Experiments on an archive of 120 hours of news video, from the 2003 TRECVID benchmark, show that a combined analysis of production phases yields the best results. In addition, we demonstrate that the accuracy of the proposed style analysis framework for classification of several rich semantic concepts is state-of-the-art.
The results of a study are presented, in which people queried a news archive using an interactive video retrieval system. 242 search sessions by 39 participants on 24 topics were assessed. Before, during and after the study, participants filled in questionnaires about their expectations of a search. The questionnaire data, logged user actions on the system, queries formulated by users, and a quality measure of each search were studied. The results of the study show that topics concerning 'specific' people or objects were better retrieved than topics concerning 'general' objects and scenes. Users were able to estimate the overall quality of a search but did not know when the optimal result was reached within the search process. Analysis of the results at various stages in the retrieval process suggests that retrieval based on transcriptions of the speech in video data adds more to the average precision of the result than content-based image retrieval based on low-level visual features. The latter is particularly useful in providing the user with an overview of the dataset and thus an indication of the success of a search. Based on the results, implications for the design of user interfaces of video retrieval systems are discussed.
Content-based image retrieval (CBIR) has been under investigation for a long time with many systems built to meet different application demands. However, in all systems, there is still a gap between the user's expectation and the system's retrieval capabilities. Therefore, user interaction is an essential component of any CBIR system. Interaction up to now has mostly focused on changing global image features or similarities between images. We consider the interaction with salient details in the image i.e. points, lines, and regions. Interactive salient detail definition goes further than summarizing the image into a set of salient details. We aim to dynamically update the user- and context-dependent definition of saliency based on relevance feedback. To that end, we propose an interaction framework for salient details from the perspective of the user. A number of instantiations of the framework are presented. Finally, we apply our approach for query refinement in detail based image retrieval system with salient points and regions. Experimental results prove the effectiveness of adapting the saliency from user feedback in the retrieval process.
We propose the Time Interval Multimedia Event (TIME) framework as a robust approach for classification of semantic events in multimodal video documents. The representation used in TIME extends the Allen time relations and allows for proper inclusion of context and synchronization of the heterogeneous information sources involved in multimodal video analysis. To demonstrate the viability of our approach, it was evaluated on the domains of soccer and news broadcasts. For automatic classification of semantic events, we compare three different machine learning techniques, i.c. C4.5 decision tree, Maximum Entropy, and Support Vector Machine. The results show that semantic video indexing results significantly benefit from using the TIME framework.
Efficient and effective handling of video documents depends on the availability of indexes. Manual indexing is unfeasible for large video collections. In this paper we survey several methods aiming at automating this time and resource consuming process. Good reviews on single modality based video indexing have appeared in literature. Effective indexing, however, requires a multimodal approach in which either the most appropriate modality is selected or the different modalities are used in collaborative fashion. Therefore, instead of separately treating the different information sources involved, and their specific algorithms, we focus on the similarities and differences between the modalities. To that end we put forward a unifying and multimodal framework, which views a video document from the perspective of its author. This framework forms the guiding principle for identifying index types, for which automatic methods are found in literature. It furthermore forms the basis for categorizing these different methods.
Effectively labeling the visual content of movies is essential for annotation. We present the interactive and adaptive i-Notation system, which describes actors names, automatically processes multimodal information sources, and deals with available sources varying quality. It provides the basis for intelligent interaction and demonstrates significant improvements in annotation efficiency.
Although various Logical Story Unit (LSU) segmentation methods based on visual content have been presented in literature, a common ground for comparison is missing. We present a systematic evaluation of the mutual dependencies of segmentation methods and their performances. LSUs are subjective and cannot be defined with full certainty. To limit subjectivity, we present definitions based on film theory. For evaluation, we introduce a method measuring the quality of a segmentation method and its economic impact rather than the amount of errors. Furthermore, the inherent complexity of the segmentation problem given a visual feature is measured. Also, we show to what extent LSU segmentation depends on the quality of shot boundary segmentation. To understand LSU segmentation, we present a unifying framework classifying segmentation methods into four essentially different types. We present results of an evaluation of the four types under similar circumstances using an unprecedented amount of 20 hours of 17 complete videos in different genres. Tools and ground truths are available for interactive use via internet.
Human-computer interaction is a decisive factor in effective content-based access to large image repositories. In current image retrieval systems the user refines his query by selecting example images from a relevance ranking. Since the top ranked images are all similar, user feedback often results in rearrangement of the presented images only. For better incorporation of user interaction in the retrieval process, we have developed the Filter Image Browsing method. It also uses feedback through image selection. However, it is based on differences between images rather than similarities. Filter Image Browsing presents overviews of relevant parts of the database to users. Through interaction users then zoom in on parts of the image collection. By repeatedly limiting the information space, the user quickly ends up with a small amount of relevant images. The method can easily be extended for the retrieval of multimedia objects.For evaluation of the Filter Image Browsing retrieval concept, a user simulation is applied to a pictorial database containing 10,000 images acquired from the World Wide Web by a search robot. The simulation incorporates uncertainty in the definition of the information need by users. Results show Filter Image Browsing outperforms plain interactive similarity ranking in required effort from the user. Also, the method produces predictable results for retrieval sessions, so that the user quickly knows if a successful session is possible at all. Furthermore, the simulations show the overview techniques are suited for applications such as hand-held devices where screen space is limited.
The paper presents a review of 200 references in content-based image retrieval. The paper starts with discussing the working conditions of content-based retrieval: patterns of use, types of pictures, the role of semantics, and the sensory gap. Subsequent sections discuss computational steps for image retrieval systems. Step one of the review is image processing for retrieval sorted by color, texture, and local geometry. Features for retrieval are discussed next, sorted by: accumulative and global features, salient points, object and shape features, signs, and structural combinations thereof. Similarity of pictures and objects in pictures is reviewed for each of the feature types, in close connection to the types and means of feedback the user of the systems is capable of giving by interaction. We briefly discuss aspects of system engineering: databases, system architecture, and evaluation. In the concluding section, we present our view on: the driving force of the field, the heritage from computer vision, the influence on computer vision, the role of similarity and of interaction, the need for databases, the problem of evaluation, and the role of the semantic gap.
Content-based video retrieval is maturing to the point where it can be used in real-world retrieval practices. One such practice is the audiovisual archive, whose users increasingly require fine-grained access to broadcast television content. We investigate to what extent content-based video retrieval methods can improve search in the audiovisual archive. In particular, we propose an evaluation methodology tailored to the specific needs and circumstances of the audiovisual archive, which are typically missed by existing evaluation initiatives. We utilize logged searches and content purchases from an existing audiovisual archive to create realistic query sets and relevance judgments. To reflect the retrieval practice of both the archive and the video retrieval community as closely as possible, our experiments with three video search engines incorporate archive-created catalog entries as well as state-of-the-art multimedia content analysis results. We find that incorporating content-based video retrieval into the archive’s practice results in significant performance increases for shot retrieval and for retrieving entire television programs. Our experiments also indicate that individual content-based retrieval methods yield approximately equal performance gains. We conclude that the time has come for audiovisual archives to start accommodating content-based video retrieval methods into their daily practice.
Automatic visual categorization is critically dependent on labeled examples for supervised learning. As an alternative to traditional expert labeling, social-tagged multimedia is becoming a novel yet subjective and inaccurate source of learning examples. Different from existing work focusing on collecting positive examples, we study in this paper the potential of substituting social tagging for expert labeling for creating negative examples. We present an empirical study using 6.5 million Flickr photos as a source of social tagging. Our experiments on the PASCAL VOC challenge 2008 show that with a relative loss of only 4.3% in terms of mean average precision, expert-labeled negative examples can be completely replaced by social-tagged negative examples for consumer photo categorization.
Automatic image tagging is important yet challenging due to the semantic gap and the lack of learning examples to model a tag's visual diversity. Meanwhile, social user tagging is creating rich multimedia content on the web. In this paper, we propose to combine the two tagging approaches in a search-based framework. For an unlabeled image, we first retrieve its visual neighbors from a large user-tagged image database. We then select relevant tags from the result images to annotate the unlabeled image. To tackle the unreliability and sparsity of user tagging, we introduce a joint-modality tag relevance estimation method which efficiently addresses both textual and visual clues. Experiments on 1.5 million Flickr photos and 10 000 Corel images verify the proposed method.
This paper seeks to unravel whether commonly available social tagged images can be exploited as a training resource for concept-based video search. Since social tags are known to be ambiguous, overly personalized, and often error prone, we place special emphasis on the role of disambiguation. We present a systematic experimental study that evaluates concept detectors based on social tagged images, and their disambiguated versions, in three application scenarios: within-domain, cross-domain, and together with an interacting user. The results indicate that social tagged images can aid concept-based video search indeed, especially after disambiguation and when used in an interactive video retrieval setting. These results open-up interesting avenues for future research.
The Microsoft SenseCam is a small lightweight wearable camera used to passively capture photos and other sensor readings from a user's day-to-day activities. It can capture up to 3,000 images per day, equating to almost 1 million images per year. It is used to aid memory by creating a personal multimedia lifelog, or visual recording of the wearer's life. However the sheer volume of image data captured within a visual lifelog creates a number of challenges, particularly for locating relevant content. Within this work, we explore the applicability of semantic concept detection, a method often used within video retrieval, on the novel domain of visual lifelogs. A concept detector models the correspondence between low-level visual features and high-level semantic concepts (such as indoors, outdoors, people, buildings, etc.) using supervised machine learning. By doing so it determines the probability of a concept's presence. We apply detection of 27 everyday semantic concepts on a lifelog collection composed of 257,518 SenseCam images from 5 users. The results were then evaluated on a subset of 95,907 images, to determine the precision for detection of each semantic concept and to draw some interesting inferences on the lifestyles of those 5 users. We additionally present future applications of concept detection within the domain of lifelogging.
Social image retrieval is important for exploiting the increasing amounts of amateur-tagged multimedia such as Flickr images. Since amateur tagging is known to be uncontrolled, ambiguous, and personalized, a fundamental problem is how to reliably interpret the relevance of a tag with respect to the visual content it is describing. Intuitively, if different persons label similar images using the same tags, these tags are likely to reflect objective aspects of the visual content. Starting from this intuition, we propose a novel algorithm that scalably and reliably learns tag relevance by accumulating votes from visually similar neighbors. Further, treated as tag frequency, learned tag relevance is seamlessly embedded into current tag-based social image retrieval paradigms. Preliminary experiments on one million Flickr images demonstrate the potential of the proposed algorithm. Overall comparisons for both single-word queries and multiple-word queries show substantial improvement over the baseline by learning and using tag relevance. Specifically, compared with the baseline using the original tags, on average, retrieval using improved tags increases mean average precision by 24%, from 0.54 to 0.67. Moreover, simulated experiments indicate that performance can be improved further by scaling up the amount of images used in the proposed neighbor voting algorithm.
Various query methods for video search exist. Because of the semantic gap each method has its limitations. We argue that for effective retrieval query methods need to be combined at retrieval time. However, switching query methods often involves a change in query and browsing interface, which puts a heavy burden on the user. In this paper, we propose a novel method for fast and effective search trough large video collections by embedding multiple query methods into a single browsing environment. To that end we introduced the notion of query threads, which contain a shot-based ranking of the video collection according to some feature-based similarity measure. On top of these threads we define several thread-based visualizations, ranging from fast targeted search to very broad exploratory search, with the ForkBrowser as the balance between fast search and video space exploration. We compare the effectiveness and efficiency of the ForkBrowser with the CrossBrowser on the TRECVID 2007 interactive search task. Results show that different query methods are needed for different types of search topics, and that the ForkBrowser requires signifficantly less user interactions to achieve the same result as the CrossBrowser. In addition, both browsers rank among the best interactive retrieval systems currently available.
Concept classification is important to access visual information on the level of objects and scene types. So far, intensity-based features have been widely used. To increase discriminative power, color features have been proposed only recently. As many features exist, a structured overview is required of color features in the context of concept classification. Therefore, this paper studies 1. the invariance properties and 2. the distinctiveness of color features in a structured way. The invariance properties of color features with respect to photometric changes are summarized. The distinctiveness of color features is assessed experimentally using an image and a video benchmark: the PASCAL VOC Challenge 2007 and the Mediamill Challenge. Because color features cannot be studied independently from the points at which they are extracted, different point sampling strategies based on Harris-Laplace salient points, dense sampling and the spatial pyramid are also studied. From the experimental results, it can be derived that invariance to light intensity changes and light color changes affects concept classification. The results reveal further that the usefulness of invariance is concept-specific.
Image category recognition is important to access visual information on the level of objects and scene types. So far, intensity-based descriptors have been widely used. To increase illumination invariance and discriminative power, color descriptors have been proposed only recently. As many descriptors exist, a structured overview of color invariant descriptors in the context of image category recognition is required. Therefore, this paper studies the invariance properties and the distinctiveness of color descriptors in a structured way. The invariance properties of color descriptors are shown analytically using a taxonomy based on invariance properties with respect to photometric transformations. The distinctiveness of color descriptors is assessed experimentally using two benchmarks from the image domain and the video domain. From the theoretical and experimental results, it can be derived that invariance to light intensity changes and light color changes affects category recognition. The results reveal further that, for light intensity changes, the usefulness of invariance is category-specific.
Category recognition is important to access visual information on the level of objects. A common approach is to compute image descriptors first and then to apply machine learning to achieve category recognition from annotated examples. As a consequence,the choice of image descriptors is of great influence on the recognition accuracy. So far, intensity-based (e.g. SIFT) descriptors computed at salient points have been used. However, color has been largely ignored. The question is, can color information improve accuracy of category recognition? Therefore, in this paper, we will extend both salient point detection and region description with color information. The extension of color descriptors is integrated into the framework of category recognition enabling to select both intensity and color variants. Our experiments on an image benchmark show that category recognition benefits from the use of color. Moreover, the combination of intensity and color descriptors yields a 30% improvement over intensity features alone.
This paper describes a novel method for browsing a large collection of news video by linking various forms of related video fragments together as threads. Each thread contains a sequence of shots with high feature-based similarity. Two interfaces are designed which use threads as the basis for browsing. One interface shows a minimal set of threads, and the other as many as possible. Both interfaces are evaluated in the TRECVID interactive retrieval task, where they ranked among the best interactive retrieval systems currently available. The results indicate that the use of threads in interactive video search is very beneficial. We have found that in general the query result and the timeline are the most important threads. However, having several additional threads allow a user to find unique results which cannot easily be found by using query results and time alone.
In this paper we describe the current performance of our MediaMill system as presented in the TRECVID 2006 benchmark for video search engines. The MediaMill team participated in two tasks: concept detection and search. For concept detection we use the MediaMill Challenge as experimental platform. The MediaMill Challenge divides the generic video indexing problem into a visual-only, textual-only, early fusion, late fusion, and combined analysis experiment. We provide a baseline implementation for each experiment together with baseline results. We extract image features, on global, regional, and keypoint level, which we combine with various supervised learners. A late fusion approach of visual-only analysis methods using geometric mean was our most successful run. With this run we conquer the Challenge baseline by more than 50%. Our concept detection experiments have resulted in the best score for three concepts: i.e. desert, flag us, and charts. What is more, using LSCOM annotations, our visual-only approach generalizes well to a set of 491 concept detectors. To handle such a large thesaurus in retrieval, an engine is developed which allows users to select relevant concept detectors based on interactive browsing using advanced visualizations. Similar to previous years our best interactive search runs yield top performance, ranking 2nd and 6th overall.
This paper contributes to the automatic indexing of concert video. In contrast to traditional methods, which rely primarily on audio information for summarization applications, we explore how a visual-only concept detection approach could be employed. We investigate how our recent method for news video indexing - which takes into account the role of content and style - generalizes to the concert domain. We analyze concert video on three levels of visual abstraction, namely: content, style, and their fusion. Experiments with 12 concept detectors, on 45 hours of visually challenging concert video, show that the automatically learned best approach is concept-dependent. Moreover, these results suggest that the visual modality provides ample opportunity for more effective indexing and retrieval of concert video when used in addition to the auditory modality.
Until now, systematic studies on the effectiveness of concept detectors for video search have been carried out using less than 20 detectors, or in combination with other retrieval techniques. We investigate whether video search using just large concept detector lexicons is a viable alternative for present day approaches. We demonstrate that increasing the number of concept detectors in a lexicon yields improved video retrieval performance indeed. In addition, we show that combining concept detectors at query time has the potential to boost performance further. We obtain the experimental evidence on the automatic video search task of TRECVID 2005 using 363 machine learned concept detectors.
In this paper we present the methods underlying the MediaMill semantic video search engine. The basis for the engine is a semantic indexing process which is currently based on a lexicon of 491 concept detectors. To support the user in navigating the collection, the system defines a visual similarity space, a semantic similarity space, a semantic thread space, and browsers to explore them. We compare the different browsers and their utility within the TRECVID benchmark. In 2005, We obtained a top-3 result for 19 out of 24 search topics. In 2006 for 14 out of 24.
In this paper, we introduce a new approach to learn dissimilarity for interactive search in content based image retrieval. In literature, dissimilarity is often learned via the feature space by feature selection, feature weighting or a parameterized function of the features. Different from existing techniques, we use relevance feedback to adjust dissimilarity in a dissimilarity space. To create a dissimilarity space, we use Pekalska’s method [15]. After the user gives feedback, we apply active learning with one-class SVM on this space. Results on a Corel dataset of 10000 images and a TrecVid collection of 43907 keyframes show that our proposed approach can improve the retrieval performance over the feature space based approach.
We introduce the challenge problem for generic video indexing to gain insight in intermediate steps that affect performance of multimedia analysis methods, while at the same time fostering repeatability of experiments. To arrive at a challenge problem, we provide a general scheme for the systematic examination of automated concept detection methods, by decomposing the generic video indexing problem into 2 unimodal analysis experiments, 2 multimodal analysis experiments, and 1 combined analysis experiment. For each experiment, we evaluate generic video indexing performance on 85 hours of international broadcast news data, from the TRECVID 2005/2006 benchmark, using a lexicon of 101 semantic concepts. By establishing a minimum performance on each experiment, the challenge problem allows for component-based optimization of the generic indexing issue, while simultaneously offering other researchers a reference for comparison during indexing methodology development. To stimulate further investigations in intermediate analysis steps that influence video indexing performance, the challenge offers to the research community a manually annotated concept lexicon, pre-computed low-level multimedia features, trained classifier models, and five experiments together with baseline performance, which are all available at http://www.mediamill.nl/challenge/.
Digital video is sequential in nature. When video data is used in a semantic concept classification task, the episodes are usually summarized with shots. The shots are annotated as containing, or not containing, a certain concept resulting in a labeled dataset. These labeled shots can subsequently be used by supervised learning methods (classifiers) where they are trained to predict the absence or presence of the concept in unseen shots and episodes. The performance of such automatic classification systems is usually estimated with cross-validation. By taking random samples from the dataset for training and testing as such, part of the shots from an episode are in the training set and another part from the same episode is in the test set. Accordingly, data dependence between training and test set is introduced, resulting in too optimistic performance estimates. In this paper, we experimentally show this bias, and propose how this bias can be prevented using episode-constrained cross-validation. Moreover, we show that a 15% higher classifier performance can be achieved by using episode constrained cross-validation for classifier parameter tuning.
Much emphasis has recently been placed on the detection and recognition of locally (weak) affine invariant region descriptors for object recognition. In this paper, we take recognition one step further by developing features for non-planar objects. We consider the description of objects with locally smoothly varying surface. For this class of objects, colour invariant histogram matching has proven to be very encouraging. However, matching many local colour cubes is computationally demanding. We propose a compact colour descriptor, which we call Wiccest, requiring only 12 numbers to locally capture colour and texture information. The Wiccest features are shown to be fairly insensitive to photometric effects like shadow, shading, and illumination colour. Moreover, we demonstrate the features to be applicable to highly compressed images while retaining discriminative power.
In this paper we present the methods and visualizations used in the MediaMill video search engine. The basis for the engine is a semantic indexing process which derives a lexicon of 101 concepts. To support the user in navigating the collection, the system defines a visual similarity space, a semantic similarity space, a semantic thread space, and browsers to explore them. The search system is evaluated within the TRECVID benchmark. We obtain a top-3 result for 19 out of 24 search topics. In addition, we obtain the highest mean average precision of all search participants.
We combine in this paper automatic learning of a large lexicon of semantic concepts with traditional video retrieval methods into a novel approach to narrow the semantic gap. The core of the proposed solution is formed by the automatic detection of an unprecedented lexicon of 101 concepts. From there, we explore the combination of query-by-concept, query-by-example, query-by-keyword, and user interaction into the MediaMill semantic video search engine. We evaluate the search engine against the 2005 NIST TRECVID video retrieval benchmark, using an international broadcast news archive of 85 hours. Top ranking results show that the lexicon-driven search engine is highly effective for interactive video retrieval.
This paper presents the semantic pathfinder architecture for generic indexing of video archives. The pathfinder automatically extracts semantic concepts from video based on the exploration of different paths through three consecutive analysis steps, closely linked to the video production process, namely: content analysis, style analysis, and context analysis. The virtue of the semantic pathfinder is its learned ability to find a best path of analysis steps on a per-concept basis. To show the generality of this indexing approach we develop detectors for a lexicon of 32 concepts and we evaluate the semantic pathfinder against the 2004 NIST TRECVID video retrieval benchmark, using a news archive of 64 hours. Top ranking performance indicates the merit of the semantic pathfinder.
We present a generic and robust approach for scene categorization. A complex scene is described by proto-concepts like vegetation, water, fire, sky etc. These proto-concepts are represented by low level features, where we use natural images statistics to compactly represent color invariant texture information by a Weibull distribution. We introduce the notion of contextures which preserve the context of textures in a visual scene with an occurrence histogram (context) of similarities to proto-concept descriptors (texture). In contrast to a codebook approach, we use the similarity to all vocabulary elements to generalize beyond the code words. Visual descriptors are attained by combining different types of contexts with different texture parameters. The visual scene descriptors are generalized to visual categories by training a support vector machine. We evaluate our approach on 3 different datasets: 1) 50 categories for the TRECVID video dataset; 2) the Caltech 101-object images; 3) 89 categories being the intersection of the Corel photo stock with the Art Explosion photo stock. Results show that our approach is robust over different datasets, while maintaining competitive performance.
Pictures have always been a prime carrier of Dutch culture. But pictures take a new form. We live in times of broad- and narrowcasting through Internet, of passive and active viewers, of direct or delayed broadcast, and of digital pictures being delivered in the museum or at home. At the same time, the picture and television archives turn digital. Archives are going to be swamped with information requests unless they swiftly adapt to partially automatic annotation and digital retrieval. Our aim is to provide faster and more complete access to picture archives by digital analysis. Our approach consists of a multi-media analysis of features of pictures in tandem with the language that describes those pictures, under the guidance of a visual ontology. The general scientific paradigm we address is the detection of directly observables fused into semantic features learned from large repositories of digital video. We use invariant, natural-image statisticsbased contextual feature sets for capturing the concepts of images and integrate that as early as possible with text. The system consists of a large for science yet small for practice set of visual concepts permitting the retrieval of semantically formulated queries. We will demonstrate a PC-based, off-line trained state of the art system for browsing broadcast news-archives.
Most of the existing work in interactive content based retrieval concentrates on machine learning methods for effective use of relevance feedback. On the other end of the spectrum, the information visualization community focusses on effective methods for conveying information to the user. What lacks is research considering the information visualization and interactive content based retrieval as truly integrated parts of one search system. In such an integrated system there are many degrees of freedom like the number of images to display, the image size, different visualization modes, and possible feedback modes. To find optimal values for all of those using user studies is unfeasible. We therefore develop scenarios in which tasks and user actions are simulated. These are then optimized based on objective constraints and evaluation criteria. In such a manner the degrees of freedom are reduced and the remaining degrees can be evaluated in user studies. In this paper we present a system which integrates advanced similarity based visualization with active learning. We have performed extensive scenario based experimentation on an interactive category search task. The results show that indeed the use of advanced visualization and active learning pays off.
To ensure access to growing video collections, annotation is becoming more and more important. Using background knowledge in the form of ontologies or thesauri is a way to facilitate annotation in a broad domain. Current ontologies are not suitable for (semi-) automatic annotation of visual resources as they contain little visual information about the concepts they describe. We investigate how an ontology that does contain visual information can facilitate annotation in a broad domain and identify requirements that a visual ontology has to meet. Based on these requirements, we create a visual ontology out of two existing knowledge corpora (WordNet and MPEG-7) by creating links between visualand general concepts. We test performance of the ontology on 40 shots of news video, and discuss the added value of each visual property.
Semantic analysis of multimodal video aims to index segments of interest at a conceptual level. In reaching this goal, it requires an analysis of several information streams. At some point in the analysis these streams need to be fused. In this paper, we consider two classes of fusion schemes, namely early fusion and late fusion. The former fuses modalities in feature space, the latter fuses modalities in semantic space. We show by experiment on 184 hours of broadcast video data and for 20 semantic concepts, that late fusion tends to give slightly better performance for most concepts. However, for those concepts where early fusion performs better the difference is more significant.
Typical semantic video analysis methods aim for classification of camera shots based on extracted features from a single key frame only. In this paper, we sketch a video analysis scenario and evaluate the benefit of analysis beyond the key frame for semantic concept detection performance. We developed detectors for a lexicon of 26 concepts, and evaluated their performance on 120 hours of video data. Results show that, on average, detection performance can increase with almost 40% when the analysis method takes more visual content into account.
In literature, few content based multimedia retrieval systems take the visualization as a tool for exploring the collections. However, when searching for images without examples to start with, one needs to explore the data set. Up to now, most available systems just show random collections of images in 2D grid form. More recently, advanced techniques have been developed for browsing based on similarity. However, none of them analyze the problems that occur when visualizing large visual collections. In this paper, we make these problems explicit. From there, we establish three general requirements: overview, visibility, and data structure preservation. Solutions for each requirement are proposed. Finally, a system is presented and experimental results are given to demonstrate our theory and approach.
The Parallel-Horus framework, developed at the University of Amsterdam, is a unique software architecture that allows non-expert parallel programmers to develop fully sequential multimedia applications for efficient execution on homogeneous Beowulf-type commodity clusters. Previously obtained results for realistic, but relatively small-sized applications have shown the feasibility of the Parallel-Horus approach, with parallel performance consistently being found to be optimal with respect to the abstraction level of message passing programs. In this paper we discuss the most serious challenge Parallel-Horus has had to deal with so far: the processing of over 184 hours of video included in the 2004 NIST TRECVID evaluation, i.e. the de facto international standard benchmark for content-based video retrieval. Our results and experiences confirm that Parallel- Horus is a very powerful support-tool for state-of-the-art research and applications in multimedia processing.
We focus on the problem of learning rich semantic patterns from the multimedia data associated with broadcast video documents. In this talk we propose a generic and flexible framework for produced video classification that is capable to learn semantic concepts from multimodal sources based on analyzed style elements. Four properties that are indicative for style are identified, i.e. layout, content, capture, and concept context. The framework allows for robust classification of different semantic concepts in produced video by using a fixed core of common layout, content, and capture elements in combination with varying concept specific context elements. Concepts are classified using a Stacked Probabilistic Support Vector Machine. Results on 120 hours of video data from the 2003 TRECVID benchmark show that, by using the proposed framework, several rich semantic concepts in broadcast news can be classified with state-of-the-art accuracy.
In this paper we discuss a the support of users in adding spatial information semi-automatically to annotations of images. Descriptions of objects depicted in an image are extended with information about the position of those objects. We distinguish two types of spatial concepts: absolute positions of objects (e.g., east, west) and relative spatial relations between objects (e.g., left, above). We show the use of a tool for a collection of art paintings with preexisting RDF annotations, including a list of image objects. First, the tool segments a painting into regions. The user selects regions, and labels these with objects from the existing annotation. Then, the tool computes absolute positions and relative spatial relations of the selected regions, and adds these to the annotation. A small evaluation study is reported in which annotations generated by the tool are compared to manual annotations by ten volunteers.
In this paper, we consider the interaction with salient details in the image i.e. points, lines, and regions. Interactive salient detail definition goes further than summarizing the image into a set of salient details since the saliency of details depends on the context, the application and the user. We propose an interaction framework for salient details from the perspective of the user, which dynamically updates the user- and context-dependent definition of saliency based on relevance feedback. A number of instantiations of the framework are presented.
In any CBIR system, visualization is important, either to show the final result to the user or to form the basis for interaction. Advanced systems use 2-dimensional similarity based visualization which show not only the information of one image itself but also the relations between images. A problem in interactive 2D visualization is the overlap between the images displayed. This obviously reduces the search capability. Simply spreading the images on the screen space will not preserve the relations between them. In this paper, we propose a visualization scheme which reduces the overlap as well as preserves the general distribution of the images displayed. Results show that an effective balance between display of structures and limited overlap can be achieved.
We propose a method for detection of semantic concepts in produced video based on style analysis. Recognition of concepts is done by applying a classifier ensemble to the detected style elements. As a case study we present a method for detecting the concept of news subject monologues. Our approach had the best average precision performance amongst 26 submissions in the 2003 TRECVID benchmark.
In this presentation we present a system for interactive search in video archives. In our view interactive search is a fourstep process composed of indexing, filtering, browsing, and ranking. We have experimentally verified, using 22 groups of two participants each, how users apply these steps in the interactive search and how well they perform.
In this paper we present the results of a user study that was conducted in combination with a submission to TRECVID 2003. Search behavior of students querying an interactive video-retrieval system was analyzed. 242 Searches by 39 students on 24 topics were assessed. Questionnaire data, logged user actions on the system, and a quality mea- sure of each search provided by TRECVID were studied. Analysis of the results at various stages in the retrieval process suggests that retrieval based on transcriptions of the speech in video data adds more to the average precision of the result than content-based retrieval. The latter is particularly useful in providing the user with an overview of the dataset and thus an indication of the success of a search.
Content-based image retrieval (CBIR) has been under investigation for a long time with many systems built to meet different application demands. However, in all systems, there is still a big gap between the user's expectation and the system's retrieval capabilities. Therefore, user interaction is an essential component of any CBIR system. Interaction up to now has mostly focused on global image features or similarities. We consider the interaction with salient details in the image i.e. points, lines, and regions. Interactive salient detail definition goes further than automatically summarizing the image into a set of salient details. We aim to dynamically update the user- and context-dependent definition of saliency based on relevance feedback from the user. In this paper, we propose an interaction framework for salient details from the perspective of the user.
Multimodal indexing of events in video documents poses problems with respect to representation, inclusion of contextual information, and synchronization of the heterogeneous information sources involved. In this paper we present the Time Interval Maximum Entropy (TIME) framework that tackles aforementioned problems. To demonstrate the viability of TIME for event classification in multimodal video, an evaluation was performed on the domain of soccer broadcasts. It was found that by applying TIME, the amount of video a user has to watch in order to see almost all highlights can be reduced considerably.
Efficient and effective handling of video documents depends on the availability of indexes. Manual indexing is unfeasible for large video collections. Efficient, single modality based, video indexing methods have appeared in literature. Effective indexing, however, requires a multimodal approach in which either the most appropriate modality is selected or the different modalities are used in collaborative fashion. In this paper we present a framework for multimodal video indexing, which views a video document from the perspective of its author. The framework serves as a blueprint for a generic and flexible multimodal video indexing system, and generalizes different state-of-the-art video indexing methods. It furthermore forms the basis for categorizing these different methods.
The indexing and retrieval of multimedia items is difficult due to the semantic gap between the user's perception of the data and the descriptions we can derive automatically from the data using computer vision, speech recognition, and natural language processing. In this contribution we consider the nature of the semantic gap in more detail and show examples of methods that help in limiting the gap. These methods can be automatic, but in general the indexing and retrieval of multimedia items should be a collaborative process between the system and the user. We show how to employ the user's interaction for limiting the semantic gap.
In this paper we describe our TRECVID 2009 video retrieval experiments. The MediaMill team participated in three tasks: concept detection, automatic search, and interactive search. The starting point for the MediaMill concept detection approach is our top-performing bag-of-words system of last year, which uses multiple color descriptors, codebooks with soft-assignment, and kernel-based supervised learning. We improve upon this baseline system by exploring two novel research directions. Firstly, we study a multi-modal extension by including 20 audio concepts and fusion using two novel multi-kernel supervised learning methods. Secondly, with the help of recently proposed algorithmic refinements of bag-of-word representations, a GPU implementation, and compute clusters, we scale-up the amount of visual information analyzed by an order of magnitude, to a total of 1,000,000 i-frames. Our experiments evaluate the merit of these new components, ultimately leading to 64 robust concept detectors for video retrieval. For retrieval, a robust but limited set of concept detectors justifies the need to rely on as many auxiliary information channels as possible. For automatic search we therefore explore how we can learn to rank various information channels simultaneously to maximize video search results for a given topic. To further improve the video retrieval results, our interactive search experiments investigate the roles of visualizing preview results for a certain browse-dimension and relevance feedback mechanisms that learn to solve complex search topics by analysis from user browsing behavior. The 2009 edition of the TRECVID benchmark has again been a fruitful participation for the MediaMill team, resulting in the top ranking for both concept detection and interactive search. Again a lot has been learned during this year's TRECVID campaign; we highlight the most important lessons at the end of this paper.
In this paper we describe our TRECVID 2008 video retrieval experiments. The MediaMill team participated in three tasks: concept detection, automatic search, and interactive search. Rather than continuing to increase the number of concept detectors available for retrieval, our TRECVID 2008 experiments focus on increasing the robustness of a small set of detectors using a bag-of-words approach. To that end, our concept detection experiments emphasize in particular the role of visual sampling, the value of color invariant features, the influence of codebook construction, and the effectiveness of kernel-based learning parameters. For retrieval, a robust but limited set of concept detectors necessitates the need to rely on as many auxiliary information channels as possible. Therefore, our automatic search experiments focus on predicting which information channel to trust given a certain topic, leading to a novel framework for predictive video retrieval. To improve the video retrieval results further, our interactive search experiments investigate the roles of visualizing preview results for a certain browse-dimension and active learning mechanisms that learn to solve complex search topics by analysis from user browsing behavior. The 2008 edition of the TRECVID benchmark has been the most successful MediaMill participation to date, resulting in the top ranking for both concept detection and interactive search, and a runner-up ranking for automatic retrieval. Again a lot has been learned during this year's TRECVID campaign; we highlight the most important lessons at the end of this paper.
In this paper we describe our TRECVID 2007 experiments. The MediaMill team participated in two tasks: concept detection and search. For concept detection we extract region-based image features, on grid, keypoint, and segmentation level, which we combine with various supervised learners. In addition, we explore the utility of temporal image features. A late fusion approach of all region-based analysis methods using geometric mean was our most successful run. What is more, using MediaMill Challenge and LSCOM annotations, our visual-only approach generalizes to a set of 572 concept detectors. To handle such a large thesaurus in retrieval, an engine is developed which automatically selects a set of relevant concept detectors based on text matching, ontology querying, and visual concept likelihood. The suggestion engine is evaluated as part of the automatic search task and forms the entry point for our interactive search experiments. For this task we experiment with two browsers for interactive exploration: the well-known CrossBrowser and the novel ForkBrowser. It was found that, while retrieval performance varies substantially per topic, the ForkBrowser is able to produce the same overall results as the CrossBrowser. However, the ForkBrowser obtains top-performance for most topics with less user interaction. Indicating the potential of this browser for interactive search. Similar to previous years our best interactive search runs yield high overall performance, ranking 3rd and 4th.
In this paper we describe our TRECVID 2006 experiments. The MediaMill team participated in two tasks: concept detection and search. For concept detection we use the MediaMill Challenge as experimental platform. The MediaMill Challenge divides the generic video indexing problem into a visual-only, textual-only, early fusion, late fusion, and combined analysis experiment. We provide a baseline implementation for each experiment together with baseline results, which we made available for the TRECVID community. The Challenge package was downloaded more than 80 times and we anticipate that it has been used by several teams for their 2006 submission. Our Challenge experiments focus specifically on visual-only analysis of video (run id: B_MM). We extract image features, on global, regional, and keypoint level, which we combine with various supervised learners. A late fusion approach of visual-only analysis methods using geometric mean was our most successful run. With this run we conquer the Challenge baseline by more than 50%. Our concept detection experiments have resulted in the best score for three concepts: i.e. desert, flag us, and charts. What is more, using LSCOM annotations, our visual-only approach generalizes well to a set of 491 concept detectors. To handle such a large thesaurus in retrieval, an engine is developed which automatically selects a set of relevant concept detectors based on text matching and ontology querying. The suggestion engine is evaluated as part of the automatic search task (run id: A-MM) and forms the entry point for our interactive search experiments (run id: A-MM). Here we experiment with query by object matching and two browsers for interactive exploration: the CrossBrowser and the novel NovaBrowser. It was found that the NovaBrowser is able to produce the same results as the CrossBrowser, but with less user interaction. Similar to previous years our best interactive search runs yield top performance, ranking 2nd and 6th overall. Again a lot has been learned during this year's TRECVID campaign, we highlight the most important lessons at the end of this paper.
In this paper we describe our TRECVID 2005 experiments. The UvA-MediaMill team participated in four tasks. For the detection of camera work (runid: A_CAM) we investigate the benefit of using a tessellation of detectors in combination with supervised learning over a standard approach using global image information. Experiments indicate that average precision results increase drastically, especially for pan (+51%) and tilt (+28%). For concept detection we propose a generic approach using our semantic pathfinder. Most important novelty compared to last years system is the improved visual analysis using proto-concepts based on Wiccest features. In addition, the path selection mechanism was extended. Based on the semantic pathfinder architecture we are currently able to detect an unprecedented lexicon of 101 semantic concepts in a generic fashion. We performed a large set of experiments (runid: B_vA). The results show that an optimal strategy for generic multimedia analysis is one that learns from the training set on a per-concept basis which tactic to follow. Experiments also indicate that our visual analysis approach is highly promising. The lexicon of 101 semantic concepts forms the basis for our search experiments (runid: B_2_A-MM). We participated in automatic, manual (using only visual information), and interactive search. The lexicon-driven retrieval paradigm aids substantially in all search tasks. When coupled with interaction, exploiting several novel browsing schemes of our semantic video search engine, results are excellent. We obtain a top-3 result for 19 out of 24 search topics. In addition, we obtain the highest mean average precision of all search participants. We exploited the technology developed for the above tasks to explore the BBC rushes. Most intriguing result is that from the lexicon of 101 visual-only models trained for news data 25 concepts perform reasonably well on BBC data also.
This year the UvA-MediaMill team participated in the Feature Extraction and Search Task. We developed a generic approach for semantic concept classification using the semantic value chain. The semantic value chain extracts concepts from video documents based on three consecutive analysis links, named the content link, the style link, and the context link. Various experiments within the analysis links were performed, showing amongst others the merit of processing beyond key frames, the value of style elements, and the importance of learning semantic context. For all experiments a lexicon of 32 concepts was exploited, 10 of which are part of the Feature Extraction Task. Top three system-based ranking in 8 out of the 10 benchmark concepts indicates that our approach is very promising. Apart from this, the lexicon of 32 concepts proved very useful in an interactive search scenario with our semantic video search engine, where we obtained the highest mean average precision of all participants.
In this technical demonstration, we showcase a multimedia search engine that facilitates semantic access to archival rock n' roll concert video. The key novelty is the crowdsourcing mechanism, which relies on online users to improve, extend, and share, automatically detected results in video fragments using an advanced timeline-based video player. The user-feedback serves as valuable input to further improve automated multimedia retrieval results, such as automatically detected concepts and automatically transcribed interviews. The search engine has been operational online to harvest valuable feedback from rock n' roll enthusiasts.
In this video demonstration, we advertise the MediaMill video search engine, a system that facilitates semantic access to video based on a large lexicon of visual concept detectors and interactive video browsers. With an ultimate aim to disseminate video retrieval research to a non-technical audience, we explain the need for a visual video retrieval solution, summarize the MediaMill technology, and hint at future perspectives.
In this technical demonstration we showcase the MediaMill Semantic Video Search Engine. It allows usage of multiple query methods embedded into a single browsing environment while guiding the user to better results by using a novel active learning strategy. This allows for fast and effective search trough large video collections.
In this technical demonstration we showcase the MediaMill ForkBrowser for video retrieval. It embeds multiple query methods into a single browsing environment. We show that users can switch query methods on demand without the need to adapt to a different interface. This allows for fast and effective search trough large video collections.
In this demonstration we showcase an interactive analysis tool for researchers working on concept-based video retrieval. By visualizing intermediate concept detection analysis stages, the tool aids in understanding the success and failure of video concept detection methods. We demonstrate the tool on the domain of pop concert video.
In this technical demonstration we showcase the current version of the MediaMill system, a search engine that facilitates access to news video archives at a semantic level. The core of the system is a thesaurus of 500 automatically detected semantic concepts. To handle such a large thesaurus in retrieval, an engine is developed which automatically selects a set of relevant concepts based on a textual query, and an novel user interface which uses multi dimensional browsing to visualize the result set.
In this technical demonstration we showcase the RotorBrowser, A visualization within MediaMill system which uses query exploration as the basis for search in video archives.
In this technical demonstration we showcase the current version of the MediaMill system, a search engine that facilitates access to news video archives at a semantic level. The core of the system is a thesaurus of 500 automatically detected semantic concepts. To handle such a large thesaurus in retrieval, an engine is developed which automatically selects a set of relevant concepts based on the textual query and userspecified example images. The result set can be browsed easily to obtain the final result for the query.
In this technical demonstration we show the current version of the MediaMill system, a search engine that facilitates access to news video archives at a semantic level. The core of the system is a lexicon of 436 automatically detected semantic concepts. To handle such a large lexicon in retrieval, an engine is developed which automatically selects a set of relevant concepts based on the textual query and example images. The result set can be browsed easily to obtain the final result for the query.
In this paper we present our Mediamill video search engine. The basis for the engine is a semantic indexing process which derives a lexicon of 101 concepts. To support the user in navigating the collection, the system defines a visual similarity space, a semantic similarity space, a semantic thread space, and browsers to explore them. It extends upon [1] with improved browsing tools. The search system is evaluated within the TRECVID benchmark [2]. We obtain a top-3 result for 19 out of 24 search topics. In addition, we obtain the highest mean average precision of all search participants.
In this technical demonstration we showcase the MediaMill system. A search engine that facilitates access to news video archives at a semantic level. The core of the system is an unprecedented lexicon of 100 automatically detected semantic concepts. Based on this lexicon we demonstrate how users can obtain highly relevant retrieval results using query-by-concept. In addition, we show how the lexicon of concepts can be exploited for novel applications using advanced semantic visualizations. Several aspects of the MediaMill system are evaluated as part of our TRECVID 2005 efforts.
Video is about to conquer the Internet. Real-time delivery of video content is technically possible to any desktop and mobile device, even with modest connections. The main problem hampering massive (re)usage of video content today is the lack of effective content based tools that provide semantic access. In this contribution we discuss systems for both video analysis and video retrieval that facilitate semantic access to video sources. Both systems were evaluated in the 2004 TRECVID benchmark as top performers in their task.
Goalgle is a prototype search engine for soccer video. Browsing and retrieval functionality is provided by means of a web based interface. This interface allows users to jump to video segments from a collection of prerecorded and analyzed soccer matches based on queries on specific players, events, matches, and/or text. In this contribution we discuss the system architecture and functionality of the Goalgle soccer video search engine.
To search for images in a small collection, it can be done by just looking at them one-by-one. The sizes of image collections on the web or professional collections are in the order of a hundred thousand if not a million. For such collections systems should provide efficient browsing techniques. As most of the time, users are non-expert searchers the systems must have a user friendly interface. To satisfy these requirements, we design image search systems that allow the user to interact with image collections in an intuitive way. To that end, advanced visualization techniques are used in which a cloud of images is presented on the screen in such a way that similar images are presented close to each other. In this way the user's attention is pointed to the right search direction. While exploring this direction the user can give feedback to the system by indicating relevant images. The system than learns to adapt itself to get closer to the user's search expectation. We have demonstrated our proposed approach to different image collections from simple to very complicated ones such as images taken from large news video archives. The experimental results show a significant improvement in search performance over existing methods.
This thesis makes a contribution to the field of multimedia understanding. Where our ultimate aim is to structure the digital multimedia chaos by bridging the semantic gap between computable data features on one end and the semantic interpretation of the data by a user on the other end. We distinguish between produced and non-produced multimedia or video documents. We depart from the view that a produced video is the result of an authoring-driven production process. This authoring process serves as a metaphor for machine-driven understanding. We present a step-by-step extrapolation of this authoring metaphor for automatic multimedia understanding. While doing so, we cover in this thesis an extensive overview of the field, a theoretical foundation for authoring-driven multimedia understanding, state-of-the-art benchmark validation, and practical semantic video retrieval applications.
Video concept detection aims to detect high-level semantic information present in video. State-of-the-art systems are based on visual features and use machine learning to build concept detectors from annotated examples. The choice of features and machine learning algorithms is of great influence on the accuracy of the concept detector. So far, intensitybased SIFT features based on interest regions have been applied with great success in image retrieval. Features based on interest regions, also known as local features, consist of an interest region detector and a region descriptor. In contrast to using intensity information only, we will extend both interest region detection and region description with color information in this thesis. We hypothesize that automated concept detection using interest region features benefits from the addition of color information. Our experiments, using the Mediamill Challenge benchmark, show that the combination of intensity features with color features improves significantly over intensity features alone.
This paper describes a novel approach for finding threads in video material using basic clustering techniques by combining knowledge from the content-based retrieval in video material domain and the topic detection and tracking domain. For this the notion of the semantic thread as an ordered list of video shots about the same semantic subject is proposed. A method for generating semantic threads from a large collection of video material is presented. Several standard algorithms for creating clusters are compared and a method for including both clusters and time to create threads is discussed. With these threads an interface for searching through a large dataset of video material is proposed and implemented. This interface is then evaluated with the TRECVID interactive retrieval task, where it ranked among the best interactive retrieval systems currently available. The interface proved to be very usefull for finding video material where the topic cannot be easily found by using traditional keyword search.
The astounding rate at which digital video is becoming available has stimulated research into video retrieval systems that incorporate visual, auditory, and spatio-temporal analysis. In the beginning, these multimodal systems required intensive user interaction, but during the past few years automatic search systems that need no interaction at all have emerged, requiring only a string of natural language text and a number of multimodal examples as input. We apply ourselves to this task of automatic search, and investigate the feasibility of automatic search without multimodal examples. The result is AutoSeek, an automatic multimodal search system that requires only text as input. In our search strategy we first extract semantic concepts from text and match them to semantic concept indices using a large lexical database. Queries are then created for the semantic concept indices as well as for indices that incorporate ASR text. Finally, the result sets from the different indices are fused with a combination strategy that was created using a set of development search statements. We subject our system to an external assessment in the form of the TRECVID 2005 automatic search task, and find that our system performs competitively when compared to systems that also use multimodal examples, ranking in the top three systems for 25% of the search tasks and scoring the fourth highest in overall mean average precision. We conclude that automatic search without using multimodal examples is a realistic task, and predict that performance will improve further as semantic concept detectors increase in quantity and quality.
In this thesis we describe a method that automatically indexes shots from cinematographic video data based on the camera distance used. The proposed method can be used for automatic analysis and interpretation of the meaning of the shot within a video stream, as an assistance tool for video librarians, and as indexing mechanism to be used within a video database system. Three types of camera distance, originating from the art of filming, are distinguished. Based on extracted and evaluated visual features an integrated classification method is proposed and evaluated. It was found that, although discriminative power of some features was limited, classification of cinematographic video based on visual features is possible in the majority of shots.