C4.5: Programs for Machine Learning (書評)

Several rapid scene analysis algorithms for detecting scene changes and flashlight scenes directly on compressed video are proposed. These algorithms operate on the DC sequence which can be readily extracted from video compressed using Motion JPEG or MPEG without full-frame decompression. The DC images occupy only a small fraction of the original data size while retaining most of the essential "global" information. Operating on these images offers a significant computation saving. Experimental results show that the proposed algorithms are fast and effective in detecting abrupt scene changes, gradual transitions including fade-ins and fade-outs, flashlight scenes and in deriving intrashot variations.

Rapid scene analysis on compressed video

A number of automated shot-change detection methods for indexing a video sequence to facilitate browsing and retrieval have been proposed. Many of these methods use color histograms or features computed from block motion or compression parameters to compute frame differences. It is important to evaluate and characterize their performance so as to deliver a single set of algorithms that may be used by other researchers for indexing video databases. We present the results of a performance evaluation and characterization of a number of shot-change detection methods that use color histograms, block motion matching, or MPEG compressed data.

Performance characterization of video-shot-change detection methods

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.

/pdf/multimodal-video-indexing-a-review-of-the-state-of-the-art-2vyybm3bil.pdf

Multimodal Video Indexing: A Review of the State-of-the-art

Video shot detection and characterization for video databases

One of the challenging problems in video databases is the organization of video information. Segmenting a video into a number of clips and characterizing each clip has been suggested as one mechanism for organizing video information. This approach requires a suitable method to automatically locate cut points in a video. One way of finding such cut points is to determine the boundaries between consecutive camera shots. In this paper, we address this as a statistical hypothesis testing problem and present three tests to determine cut locations. All the three tests are such that they can be applied directly to the compressed video. This avoids an unnecessary decompression-compression cycle, since it is common to store and transmit digital video in compressed form. As our experimental results indicate, the statistical approach permits accurate detection of scene changes induced through straight as well as optical cuts.

Statistical approach to scene change detection

The zebra mussel, Dreissena polymorpha, was recently introduced accidentally into the Great Lakes and, due in part to its prodigious reproductive capacity, is spreading rapidly in temperate fresh waters of North America The present studies examine some of the mechanisms that regulate spawning in this animal In August and September 1990 and in May 1991 injection of serotonin (5-hydroxytryptamine, 5-HT) induced ripe male, but not female, zebra mussels to spawn During mid-summer 1991, 5-HT induced spawning in both males and females, and 5-HT could produce spawning responses by either injection or external application External pH over a broad range (60 to 91) had no effect on spawning, neither inhibiting induction of spawning by 5-HT nor significantly eliciting spawning itself With external application, 10(-3) M and 10(-4) M 5-HT caused spawning, but 10(-5) M and 10(-6) M did not Cyproheptadine, a 5-HT receptor antagonist, reduced the response of both males and females by more than half Spawning in response to 5-HT was blocked at 4 degrees C, but not at 12 degrees C, 20 degrees C, or 27 degrees C For male zebra mussels morphological criteria for judging gonadal maturity were well-correlated with probability of spawning in response to 5-HT For females, the likelihood of spawning in response to 5-HT was not tightly coupled to morphological maturity of the gonad, with many morphologically ripe females failing to spawn and some apparently immature animals releasing oocytes Prior spawning reduced subsequent responsiveness and intensity of spawning of animals to 5-HT These experiments support a role for 5-HT in regulating reproduction in zebra mussels and help define conditions by which zebra mussel spawning may be stimulated or inhibited

Spawning in the zebra mussel (Dreissena polymorpha): activation by internal or external application of serotonin.

The major problem facing video databases is that of content characterization of video clips once the cut boundaries have been determined. The current efforts in this direction are focussed exclusively on the use of pictorial information, thereby neglecting an important supplementary source of content information, i.e. the embedded audio or sound track. The current research in audio processing can be readily applied to create many different video indices for use in Video On Demand (VOD), educational video indexing, sports video characterization, etc. MPEG is an emerging video and audio compression standard with rapidly increasing popularity in multimedia industry. Compressed bit stream processing has gained good recognition among the researchers. We have also demonstrated feature extraction in MPEG compressed video which implements a majority of scene change detection schemes on compressed video. In this paper, we examine the potential of audio information for content characterization by demonstrating the extraction of widely used features in audio processing directly from compressed data stream and their application to video clip classification.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Audio characterization for video indexing

One of the challenging problems in video databases is the organisation of video information. Segmenting a video into a number of clips and characterising each clip has been suggested as one mechanism for organising video information. This approach requires a suitable method to automatically locate cut points (boundaries between consecutive camera shots in a video). Several existing techniques solve this problem using uncompressed video. Since video is increasingly being captured, moved, and stored in compressed form, there is a need for detecting shot boundaries directly in compressed video. The authors address this issue and show certain feature extraction steps in MPEG compressed video that allow the implementation of most of the existing cut detection methods developed for uncompressed video for MPEG video stream. They also examine the performance of three tests for cut detection by viewing the problem of cut detection as a statistical hypothesis testing problem. As the experimental results indicate, the statistical hypothesis testing approach permits fast and accurate detection of video cuts.

Nilesh V. Patel

Papers

Video shot detection and characterization for video databases

Statistical approach to scene change detection

Spawning in the zebra mussel (Dreissena polymorpha): activation by internal or external application of serotonin.

Audio characterization for video indexing

Compressed video processing for cut detection