Compact representations of video data can enable efficient video browsing. Such representations provide the user with information about the content of the particular sequence being examined while preserving the essential message. We propose a method to automatically generate video summaries for long videos. Our video summarization approach involves mainly two tasks: first, segmenting the video into small, coherent segments and second, ranking the resulting segments. Our proposed algorithm scores segments based on word frequency analysis of speech transcripts. Then a summary is generated by selecting the segments with the highest score to duration ratios and these are concatenating them. We have designed and performed a user study to evaluate the quality of summaries generated. Comparisons are made using our proposed algorithm and a random segment selection scheme based on statistical analysis of the user study results. Finally we discuss various issues that arise in evaluation of automatically generated video summaries.

We address the problem of detecting shots of subjects that are interviewed in news sequences. This is useful since usually these kinds of scenes contain important and reusable information that can be used for other news programs. In a previous paper, we presented a technique based on a priori knowledge of the editing techniques used in news sequences which allowed a fast search of news stories (see Albiol, A. et al., 3rd Int. Conf. on Audio and Video-based Biometric Person Authentication, p.366-71, 2001). We now present a new shot descriptor technique which improves the previous search results by using a simple, yet efficient, algorithm, based on the information contained in consecutive frames. Results are provided which prove the validity of the approach

In this paper, we focus on the leaky prediction based scalable coding (LPSC) structure and present a general framework for LPSC. We demonstrate the similarity between LPSC and motion compensation based multiple description coding scheme. We show that since the information contained in the enhancement layer in LPSC is actually a mismatch between two descriptions for each frame, it cannot be guaranteed that the enhancement layer always achieves superior reconstruction quality beyond that achieved by the base layer. We derive three reconstructions for each frame under the LPSC framework, and propose a maximum-likelihood (ML) estimation scheme for LPSC video reconstruction at the decoder. This generally achieves superior decoded video quality than both the enhancement layer and the base layer.

The production of closed captions is an important but expensive process in video broadcasting. We propose a method to generate highly accurate off-line captions efficiently. Our system uses text alignment to synchronize program transcripts obtained for a video program with text produced by an automatic speech recognition (ASR) system. We will also describe the accuracy in both closed-caption text and the ASR output for a number of news programs and provide a detailed analysis of the errors that occur.

In this paper, we describe an approach that uses a combination of visual and audio features to cluster shots belonging to the same person in video programs. We use color histograms extracted from keyframes and faces, as well as cepstral coefficients derived from audio to calculate pairwise shot distances. These distances are then normalized and combined to a single confidence value which reflects our certainty that two shots contain the same person. We then use an agglomerative clustering algorithm to cluster shots based on these confidence values. We report the results of our system on a data set of approximately 8 hours of programming.

We address the problem of detecting shots of subjects that are interviewed in news sequences. This is useful since usually these kinds of scenes contain important and reusable information that can be used for other news programs. In a previous paper, we presented a technique based on a priori knowledge of the editing techniques used in news sequences which allowed a fast search of news stories. We present a new shot descriptor technique which improves the previous search results by using a simple, yet efficient algorithm, based on the information contained in consecutive frames. Results are provided which prove the validity of the approach.

Rate scalable video compression is appealing for low bit rate applications, such as video telephony and wireless communication, where bandwidth available to an application cannot be guaranteed. In this paper, we investigate a set of strategies to increase the performance of SAMCoW, a rate scalable encoder. These techniques are based on based on wavelet decomposition, spatial orientation trees, and motion compensation

In this paper, an analysis of the efficiency of three signal-to-noise ratio (SNR) scalable strategies for motion compensated video coders and their non-scalable counterpart is presented. After assuming some models and hypotheses with respect to the signals and systems involved, we have obtained the SNR of each coding strategy as a function of the decoding rate. To validate our analysis, we have compared our theoretical results with data from encodings of real video sequences. Results show that our analysis describes qualitatively the performance of each scalable strategy, and therefore, it can be useful to understand main features of each scalable technique and what factors influence their efficiency.

Recently, we proposed a method for constructing a template for efficient temporal synchronization in video watermarking. Our temporal synchronization method uses a state machine key generator for producing the watermark embedded in successive frames of video. A feature extractor allows the watermark key schedule to be content dependent, increasing the difficulty of copy and ownership attacks. It was shown that efficient synchronization can be achieved by adding temporal redundancy into the key schedule. In this paper, we explore and extend the concepts of our temporal synchronization method to spatial synchronization. The key generator is used to construct the embedded watermark of non-overlapping blocks of the video, creating a tiled structure. The autocorrelation of the tiled watermark contains local maxima or peaks with a grid-like structure, where the distance between the peaks indicates the scale of the watermark and the orientation of the peaks indicate the watermark rotation. Experimental results are obtained using digital image watermarks. Scaling and rotation attacks are investigated.

We present a new method for full-field mammogram analysis. A mammogram is analyzed region by region and is classified as normal or abnormal. We present methods for extracting features that can be used to distinguish normal and abnormal regions of a mammogram. We describe our classifier technique that uses a unique reclassification method to boost the classification performance. We have tested this technique on a set of ground-truth full-field mammograms.

Text data forms the largest bulk of digital data that people encounter and exchange daily. For this reason the potential usage of text data as a covert channel for secret communication is an imminent concern. Even though information hiding into natural language text has started to attract great interest, there has been no study on attacks against these applications. In this paper we examine the robustness of lexical steganography systems.In this paper we used a universal steganalysis method based on language models and support vector machines to differentiate sentences modified by a lexical steganography algorithm from unmodified sentences. The experimental accuracy of our method on classification of steganographically modified sentences was 84.9%. On classification of isolated sentences we obtained a high recall rate whereas the precision was low.

Line or linear structure detection is a very basic, yet important problem in image pro-  cessing and computer vision. Many line detection algorithms are based on edge detection and consider lines as extended or contiguous edges. Most techniques require that a binary edge map be first extracted from the image before line detection is performed. In this paper,  we propose a new line detection technique that is based on a model that describes spatial characteristics of line structures in an image. This line model uses simple properties of lines that include both graylevel and geometric features. The performance of the line detector on natural scenes and medical images will be shown. The technique is shown to be capable of detecting lines of different width, lines of varying width, as well as curves.