Minerva M. Yeung

An invisible watermarking technique for image verification

We propose a new method for invisibly watermarking high-quality color and gray-scale images. This method is intended for use in image verification applications, where one is interested in knowing whether the content of an image has been altered since some earlier time, perhaps because of the act of a malicious party. It consists of both a watermark stamping process which embeds a watermark in a source image, and a watermark extraction process which extracts a watermark from a stamped image. The extracted watermark can be used to determine whether the image has been altered. The processing used in the stamping and extraction processes is presented. We also discuss some advantages of this technique over other invisible watermarking techniques for the verification application; these include a high degree of invisibility, color preservation, ease of decoding, and a high degree of protection against retention of the watermark after unauthorized alterations.

Video visualization for compact presentation and fast browsing of pictorial content

Digital video archives are likely to be accessible on distributed networks which means that the data are subject to network congestion and bandwidth constraints. To enable new applications and services of digital video, it is not only important to develop tools to analyze and browse video, view query results, and formulate better searches, but also to deliver the essence of the material in compact forms. Video visualization describes the joint process of analyzing video and the subsequent derivation of representative visual presentation of the essence of the content. We propose techniques to analyze video and build a compact pictorial summary for visual presentation. A video sequence is thus condensed into a few images-each summarizing the dramatic incident taking place in a meaningful segment of the video. In particular, we present techniques to differentiate the dominance of the content in subdivisions of the segment based on analysis results, select a graphic layout pattern according to the relative dominances, and create a set of video posters, each of which is a compact, visually pleasant, and intuitive representation of the story content. The collection of video posters arranged in temporal order then forms a pictorial summary of the sequence to tell the underlying story. The techniques and compact presentations proposed offer valuable tools for new applications and services of digital video including video browsing, query, search, and retrieval in the digital libraries and over the Internet.

Can invisible watermarks resolve rightful ownerships

Digital watermarks have been proposed in recent literature as the means for copyright protection of multimedia data. In this paper we address the capability of invisible watermarking schemes to resolve copyright ownerships. We will show that rightful ownerships cannot be resolved by current watermarking schemes alone. In addition, in the absence of standardization of watermarking procedures, anyone can claim ownership of any watermarked image. Specifically, we provide counterfeit watermarking schemes that can be performed on a watermarked image to allow multiple claims of rightful ownerships. We also proposed non-invertible watermarking schemes in this paper and discuss in general the usefulness of digital watermarks in identifying the rightful copyright owners. The results, coupled with the recent attacks on some image watermarks, further imply that we have to carefully re-think our approaches to invisible watermarking of images, and re- evaluate the promises, applications and limitations of such digital means of copyright protection.

Effective and ineffective digital watermarks

We have entered an era where inexpensive and readily-available equipment can produce perfect copies of digital multimedia materials, such as CD-quality audio, publication-quality images, or digital video. In this environment, it has become easier for malicious parties to make salable copies of copyrighted content without compensation to the content owner. Many media content owners are concerned about the potential loss of revenue from multimedia piracy, especially when the content will be exposed to the Internet. Digital watermarking is seen by many as a potential solution to this problem. Many different watermarking schemes have been proposed. Often, however there is little discussion of how effective a proposed watermarking technique may be at solving a particular problem. We describe a number of proposed image-watermarking application scenarios and form a small number of watermark-application categories. Then, with these applications in mind, we discuss the desired technical properties of watermarks for each category. Finally we discuss some watermarking techniques developed by the authors, in light of the desired properties.

Retrieving and visualizing video

Like its traditional database counterpart, a digital video database management system (VDBMS) seeks to provide convenient and efficient access to the information in the database. However, unlike traditional database systems, where the focus is search and indexing techniques, video poses additional challenges and opportunities. This article addresses the special functions and Boon-Lock Yeo and Minerva M. Yeung

Invisible watermarking for image verification

In this paper we propose a new method for invisibly wa- termarking high-quality color and gray-scale images. This method is intended for use in image verification applications to determine whether the content of an image has been altered, due perhaps, to the act of a malicious party. It consists of both a watermarking pro- cess which stamps a watermark into a source image without visual degradation, and a watermark extraction process which extracts a watermark from a stamped image. The extracted watermark can be compared with the embedded watermark to determine whether the image has been altered. The processing used in the watermarking and watermark extraction processes will be presented in this paper. In addition, we shall describe some modifications that provide better security, and an adaptation of the scheme to watermark JPEG im- ages. Experimental results are reported. Some advantages of this technique over other invisible watermarking techniques for verifica- tion will be discussed; these include a high degree of invisibility, color preservation, ease of extraction, and a high degree of protec- tion against the retention of a correct watermark after alteration by a malicious party.

Video content characterization and compaction for digital library applications

In digital libraries and the Internet, large amount of data in various modalities has to be transmitted and delivered across the networks, and is subject to bandwidth constraints and network congestion. Among all multimedia data, video is the most difficult to handle, both in terms of its size and the scarcity of tools and techniques available for efficient delivery, storage and retrieval. Providing tools to help users search and browse large collections of video documents is important. Equally important are the means to deliver and present the essence of video content to the user without noticeable delay. In this paper, we focus on the characterization of video by means of automatic analysis of its visual content and the compact presentation of the underlying story content built upon the derived characteristics. We develop models to capture and characterize video by temporal events, namely, dialogues, actions and story units. We then present these events using succinct visual summaries that depict and differentiate the underlying dramatic elements in an intuitive manner. The combination of video characterization and visual summary offers significant compaction of data size in video far beyond the numbers achieved by traditional video compression, while retaining essential meanings and semantics of the content, and is particularly useful for digital library and Internet applications.

Digital watermarking for high-quality imaging

In this paper, we address the requirements, techniques and applications of digital watermarking for high-quality images. We present several classes of digital watermarking techniques defined by their appearance and application domains, specify the requirements, and summarize the current research efforts in the Image Library Applications group of the IBM Thomas J. Watson Research Center on digital watermarking of high-quality images. We hope that by addressing these issues, we can both provide a foundation for the next generation of digital watermarking techniques, and a vision for their future applications.

Classification, simplification and dynamic visualization of scene transition graphs for video browsing

The scene transition graph (STG) is a directed graph structure that compactly captures both image content and temporal flow of video. An STG offers a condensed view of the story content, serves as the summary of the clip represented, and allows nonlinear access to its story element. It can serve as a valuable tool for both the analysis of video structure and presentation of high level visual summary for video browsing applications. In this paper, we study new techniques for classification and simplification of the STG, and present better means of visualizing the graph through dynamic visual display and simplified structures. In other words, our techniques improve significantly the existing graph structure to enable more succinct presentation of the graphs which leads to more efficient utilization of the screen spaces. In addition, a technique that captures and presents visually the temporal dynamics of the video sequence is described. We have tested the graph visualization techniques on various programming types and the new tools are found to effectively handle video from a wider variety than the existing STG structure.

Adaptive public watermarking of DCT-based compressed images

We propose an adaptive scheme to embed watermark information in DCT blocks of compressed image data. our scheme is designed to avoid artifacts and prevent an increase in the bit rate of the compressed watermarked image. This is essentially done by judicious selection of appropriate blocks for watermark insertion. We also introduce a block-dependent seed generation algorithm to determine the specific coefficients to modify in a particular block. Our proposed technique is simple to implement in software, and hence suitable for real-time software-only insertion of invisible watermarks in JPEG compressed images, and MPEG or MJPEG video streams. We also demonstrate experimentally that our proposed watermarking scheme actually results in bit rate reduction of JPEG compressed images. The proposed technique can also complement existing DCT-based watermarking schemes for copy protection and detection applications.