Evaluation of automatic shot boundary detection on a large video test suite

The challenge facing the indexing of digital video information in order to support browsing and retrieval by users, is to design systems that can accurately and automatically process large amounts of heterogeneous video. The segmentation of video material into shots and scenes is the basic operation in the analysis of video content. This paper presents a detailed evaluation of a histogram-based shot cut detector based on eight hours of TV broadcast video. Our observations are that the selection of similarity thresholds for determining shot boundaries in such broadcast video is difficult and necessitates the development of systems that employ adaptive thresholding in order to address the huge variation of characteristics prevalent in TV broadcast video

Físchlár on a PDA: handheld user interface design to a video indexing, browsing and playback system

The Físchlár digital video system is a web-based system for recording, analysis, browsing and playback of TV programmes which currently has about 350 users. Although the user interface to the system is designed for desktop PCs with a large screen and a mouse, we are developing versions to allow the use of mobile devices to access the system to record and browse the video content. In this paper, the design of a PDA user interface to video content browsing is considered. We use a design framework we have developed previously to be able to specify various video browsing interface styles thus making it possible to design for all potential users and their various environments. We can then apply this to the particulars of the PDA's small, touch-sensitive screen and the mobile environment where it will be used. The resultant video browsing interfaces have highly interactive interfaces yet are simple, which requires relatively less visual attention and focusing, and can be comfortably used in a mobile situation to browse the available video contents. To date we have developed and tested such interfaces on a Revo PDA, and are in the process of developing others

Online television library: organization and content browsing for general users

This paper describes the organisational and playback features of Físchlár, a digital video library that allows users to record, browse and watch television programmes online. Programmes that can be watched and recorded are organised by personal recommendations, genre classifications, name and other attributes for access by general television users. Motivations and interactions of users with online television libraries are outlined and they are also supported by personalised library access, categorised programmes, a combined player browser with content viewing history and content marks. The combined player browser supports a user who watches a programme on different occasions in a non-sequential order

Assembling thefacebook: Using heterogeneity to understand online social network assembly

Online social networks represent a popular and diverse class of social media systems. Despite this variety, each of these systems undergoes a general process of online social network assembly, which represents the complicated and heterogeneous changes that transform newly born systems into mature platforms. However, little is known about this process. For example, how much of a network's assembly is driven by simple growth? How does a network's structure change as it matures? How does network structure vary with adoption rates and user heterogeneity, and do these properties play different roles at different points in the assembly? We investigate these and other questions using a unique dataset of online connections among the roughly one million users at the first 100 colleges admitted to Facebook, captured just 20 months after its launch. We first show that different vintages and adoption rates across this population of networks reveal temporal dynamics of the assembly process, and that assembly is only loosely related to network growth. We then exploit natural experiments embedded in this dataset and complementary data obtained via Internet archaeology to show that different subnetworks matured at different rates toward similar end states. These results shed light on the processes and patterns of online social network assembly, and may facilitate more effective design for online social systems.Comment: 13 pages, 11 figures, Proceedings of the 7th Annual ACM Web Science Conference (WebSci), 201

Polarization anisotropy in light propagation inside opal-based photonic crystals

Photonic crystals is expected to be the backbone of future optical integrated circuits. To realize this goal, light propagation and interaction with matters must be understood and controlled. In this work, we investigate the propagation of light inside opal-based photonic crystals along certain paths at the edge of its Brillouin Zone. Opal films made of polystyrene particles were prepared using self-assembly approach, the capillary deposition method. The structures and the optical properties of the resulting opals were characterized using scanning electron microscopy and polarization-resolved spectroscopy, respectively. The opal films have a face-centered cubic structure consisting of two domains showing preferential orientations. Domains in the form of ABC and ACB-type fcc crystals are oriented along the growth direction of the opal films. Light with frequencies near optical band gap shows a strong anisotropy. Light propagation inside opals depends on the polarization of the incident light. The intensity and the width of the extinction peaks for p-polarized incident light differ significantly from those of s-polarized light. The anisotropy disappears at frequencies above the optical band gap. The anisotropic light propagation is related to the strong anisotropy in equifrequency surface of band structure around the band gap. The shift of the extinction peaks and the variation of intensity of the extinction peaks will be discussed using the combination of kinematic and simplified dynamical diffraction theory

Polarization anisotropy in light propagation inside opal-based photonic crystals

Photonic crystals is expected to be the backbone of future optical integrated circuits. To realize this goal, light propagation and interaction with matters must be understood and controlled. In this work, we investigate the propagation of light inside opal-based photonic crystals along certain paths at the edge of its Brillouin Zone. Opal films made of polystyrene particles were prepared using self-assembly approach, the capillary deposition method. The structures and the optical properties of the resulting opals were characterized using scanning electron microscopy and polarization-resolved spectroscopy, respectively. The opal films have a face-centered cubic structure consisting of two domains showing preferential orientations. Domains in the form of ABC and ACB-type fcc crystals are oriented along the growth direction of the opal films. Light with frequencies near optical band gap shows a strong anisotropy. Light propagation inside opals depends on the polarization of the incident light. The intensity and the width of the extinction peaks for p-polarized incident light differ significantly from those of s-polarized light. The anisotropy disappears at frequencies above the optical band gap. The anisotropic light propagation is related to the strong anisotropy in equifrequency surface of band structure around the band gap. The shift of the extinction peaks and the variation of intensity of the extinction peaks will be discussed using the combination of kinematic and simplified dynamical diffraction theory

The Físchlár digital video recording, analysis, and browsing system

In digital video indexing research area an important technique is called shot boundary detection which automatically segments long video material into camera shots using content-based analysis of video. We have been working on developing various shot boundary detection and representative frame selection techniques to automatically index encoded video stream and provide the end users with video browsing/navigation feature. In this paper we describe a demonstrator digital video system that allows the user to record a TV broadcast programme to MPEG-1 file format and to easily browse and playback the file content online. The system incorporates the shot boundary detection and representative frame selection techniques we have developed and has become a full-featured digital video system that not only demonstrates any further techniques we will develop, but also obtains users’ video browsing behaviour. At the moment the system has a real-user base of about a hundred people and we are closely monitoring how they use the video browsing/navigation feature which the system provides

News story segmentation in the Físchlár video indexing system

This paper presents an approach to segmenting individual news stories in broadcast news programmes. The approach first performs shot boundary detection and keyframe extraction on the programme. Shots are then clustered into groups based on their colour and temporal similarity. The clustering process is controlled using the groups' statistics. After clustering, a set of criteria are applied and groups are successively eliminated in order to converge upon a set of anchorperson groups. The temporal locations of the shots in these anchorperson groups are then used to segment the programme in terms of individual news items. This work is carried out within the context of a complete video indexing, browsing and retrieval syste

Implementation and analysis of several keyframe-based browsing interfaces to digital video

In this paper we present a variety of browsing interfaces for digital video information. The six interfaces are implemented on top of Físchlár, an operational recording, indexing, browsing and playback system for broadcast TV programmes. In developing the six browsing interfaces, we have been informed by the various dimensions which can be used to distinguish one interface from another. For this we include layeredness (the number of “layers” of abstraction which can be used in browsing a programme), the provision or omission of temporal information (varying from full timestamp information to nothing at all on time) and visualisation of spatial vs. temporal aspects of the video. After introducing and defining these dimensions we then locate some common browsing interfaces from the literature in this 3-dimensional “space” and then we locate our own six interfaces in this same space. We then present an outline of the interfaces and include some user feedback