Showing papers in "IEEE Signal Processing Magazine in 2001"

Emotion recognition in human-computer interaction

Abstract: Two channels have been distinguished in human interaction: one transmits explicit messages, which may be about anything or nothing; the other transmits implicit messages about the speakers themselves. Both linguistics and technology have invested enormous efforts in understanding the first, explicit channel, but the second is not as well understood. Understanding the other party's emotions is one of the key tasks associated with the second, implicit channel. To tackle that task, signal processing and analysis techniques have to be developed, while, at the same time, consolidating psychological and linguistic analyses of emotion. This article examines basic issues in those areas. It is motivated by the PKYSTA project, in which we aim to develop a hybrid system capable of using information from faces and voices to recognize people's emotions.

The JPEG 2000 still image compression standard

Abstract: One of the aims of the standardization committee has been the development of Part I, which could be used on a royalty- and fee-free basis. This is important for the standard to become widely accepted. The standardization process, which is coordinated by the JTCI/SC29/WG1 of the ISO/IEC has already produced the international standard (IS) for Part I. In this article the structure of Part I of the JPFG 2000 standard is presented and performance comparisons with established standards are reported. This article is intended to serve as a tutorial for the JPEG 2000 standard. The main application areas and their requirements are given. The architecture of the standard follows with the description of the tiling, multicomponent transformations, wavelet transforms, quantization and entropy coding. Some of the most significant features of the standard are presented, such as region-of-interest coding, scalability, visual weighting, error resilience and file format aspects. Finally, some comparative results are reported and the future parts of the standard are discussed.

Electromagnetic brain mapping

Abstract: There has been tremendous advances in our ability to produce images of human brain function. Applications of functional brain imaging extend from improving our understanding of the basic mechanisms of cognitive processes to better characterization of pathologies that impair normal function. Magnetoencephalography (MEG) and electroencephalography (EEG) (MEG/EEG) localize neural electrical activity using noninvasive measurements of external electromagnetic signals. Among the available functional imaging techniques, MEG and EEG uniquely have temporal resolutions below 100 ms. This temporal precision allows us to explore the timing of basic neural processes at the level of cell assemblies. MEG/EEG source localization draws on a wide range of signal processing techniques including digital filtering, three-dimensional image analysis, array signal processing, image modeling and reconstruction, and, blind source separation and phase synchrony estimation. We describe the underlying models currently used in MEG/EEG source estimation and describe the various signal processing steps required to compute these sources. In particular we describe methods for computing the forward fields for known source distributions and parametric and imaging-based approaches to the inverse problem.

Multiple description coding: compression meets the network

Abstract: This article focuses on the compressed representations of pictures. The representation does not affect how many bits get from the Web server to the laptop, but it determines the usefulness of the bits that arrive. Many different representations are possible, and there is more involved in their choice than merely selecting a compression ratio. The techniques presented represent a single information source with several chunks of data ("descriptions") so that the source can be approximated from any subset of the chunks. By allowing image reconstruction to continue even after a packet is lost, this type of representation can prevent a Web browser from becoming dormant.

Imaging the body with diffuse optical tomography

Abstract: Diffuse optical tomography (DOT) is an ongoing medical imaging modality in which tissue is illuminated by near-infrared light from an array of sources, the multiply-scattered light which emerges is observed with an array of detectors, and then a model of the propagation physics is used to infer the localized optical properties of the illuminated tissue. The three primary absorbers at these wavelengths, water and both oxygenated and deoxygenated hemoglobin, all have relatively weak absorption. This fortuitous fact provides a spectral window through which we can attempt to localize absorption (primarily by the two forms of hemoglobin) and scattering in the tissue. The most important current applications of DOT are detecting tumors in the breast and imaging the brain. We introduce the basic idea of DOT and review the history of optical methods in medicine as relevant to the development of DOT. We then detail the concept of DOT, including a review of the tissue's optical properties, modes of operation for DOT, and the challenges which the development of DOT must overcome. The basics of modelling the DOT forward problem and some critical issues among the numerous implementations that have been investigated for the DOT inverse problem, with an emphasis on signal processing. We summarize with some specific results as examples of the current state of DOT research.

Digital watermarking: algorithms and applications

Abstract: Digital watermarking of multimedia content has become a very active research area over the last several years. A general framework for watermark embedding and detection/decoding is presented here along with a review of some of the algorithms for different media types described in the literature. We highlight some of the differences based on application such as copyright protection, authentication, tamper detection, and data hiding as well as differences in technology and system requirements for different media types such as digital images, video, audio and text.

A tutorial on modern lossy wavelet image compression: foundations of JPEG 2000

Abstract: One of the purposes of this article is to give a general audience sufficient background into the details and techniques of wavelet coding to better understand the JPEG 2000 standard. The focus is on the fundamental principles of wavelet coding and not the actual standard itself. Some of the confusing design choices made in wavelet coders are explained. There are two types of filter choices: orthogonal and biorthogonal. Orthogonal filters have the property that there are energy or norm preserving. Nevertheless, modern wavelet coders use biorthogonal filters which do not preserve energy. Reasons for these specific design choices are explained. Another purpose of this article is to compare and contrast "early" wavelet coding with "modern" wavelet coding. This article compares the techniques of the modern wavelet coders to the subband coding techniques so that the reader can appreciate how different modern wavelet coding is from early wavelet coding. It discusses basic properties of the wavelet transform which are pertinent to image compression. It builds on the background material in generic transform coding given, shows that boundary effects motivate the use of biorthogonal wavelets, and introduces the symmetric wavelet transform. Subband coding or "early" wavelet coding method is discussed followed by an explanation of the EZW coding algorithm. Other modern wavelet coders that extend the ideas found in the EZW algorithm are also described.

Genomic signal processing

Abstract: Genomics is a highly cross-disciplinary field that creates paradigm shifts in such diverse areas as medicine and agriculture. It is believed that many significant scientific and technological endeavors in the 21st century will be related to the processing and interpretation of the vast information that is currently revealed from sequencing the genomes of many living organisms, including humans. Genomic information is digital in a very real sense; it is represented in the form of sequences of which each element can be one out of a finite number of entities. Such sequences, like DNA and proteins, have been mathematically represented by character strings, in which each character is a letter of an alphabet. In the case of DNA, the alphabet is size 4 and consists of the letters A, T, C and G; in the case of proteins, the size of the corresponding alphabet is 20. As the list of references shows, biomolecular sequence analysis has already been a major research topic among computer scientists, physicists, and mathematicians. The main reason that the field of signal processing does not yet have significant impact in the field is because it deals with numerical sequences rather than character strings. However, if we properly map a character string into, one or more numerical sequences, then digital signal processing (DSP) provides a set of novel and useful tools for solving highly relevant problems. For example, in the form of local texture, color spectrograms visually provide significant information about biomolecular sequences which facilitates understanding of local nature, structure, and function. Furthermore, both the magnitude and the phase of properly defined Fourier transforms can be used to predict important features like the location and certain properties of protein coding regions in DNA. Even the process of mapping DNA into proteins and the interdependence of the two kinds of sequences can be analyzed using simulations based on digital filtering. These and other DSP-based approaches result in alternative mathematical formulations and may provide improved computational techniques for the solution of useful problems in genomic information science and technology.

Theoretical foundations of transform coding

Abstract: Discusses various aspects of transform coding, including: source coding, constrained source coding, the standard theoretical model for transform coding, entropy codes, Huffman codes, quantizers, uniform quantization, bit allocation, optimal transforms, transforms visualization, partition cell shapes, autoregressive sources, transform optimization, synthesis transform optimization, orthogonality and independence, and departures form the standard model.

Audiovisual speech processing

Abstract: We have reported activities in audiovisual speech processing, with emphasis on lip reading and lip synchronization. These research results have shown that, with lip reading, it is possible to enhance the reliability of audio speech recognition, which may result in a computer that can truly understand the user via hand-free natural spoken language even in a very noisy environments. Similarly, with lip synchronization, it is possible to render realistic talking heads with lip movements synchronized with the voice, which is very useful for human-computer interactions. We envision that in the near future, advancement in audiovisual speech processing will greatly increase the usability of computers. Once that happens, the cameras and the microphone may replace the keyboard and the mouse as better mechanisms for human-computer interaction.

Wavelets, approximation, and compression

Abstract: Over the last decade or so, wavelets have had a growing impact on signal processing theory and practice, both because of the unifying role and their successes in applications. Filter banks, which lie at the heart of wavelet-based algorithms, have become standard signal processing operators, used routinely in applications ranging from compression to modems. The contributions of wavelets have often been in the subtle interplay between discrete-time and continuous-time signal processing. The purpose of this article is to look at wavelet advances from a signal processing perspective. In particular, approximation results are reviewed, and the implication on compression algorithms is discussed. New constructions and open problems are also addressed.

Hand modeling, analysis and recognition

Abstract: Analyzing hand gestures is a comprehensive task involving motion modeling, motion analysis, pattern recognition, machine learning and even psycholinguistic studies. A comprehensive review of various techniques in hand modeling, analysis, and recognition is needed. Due to the multidisciplinary nature of this research topic, we cannot include all the works in the literature. Rather than function as a thorough review paper, this article serves as a tutorial to this research topic. We study 3-D hand models, various articulated motion analysis methods, and gesture recognition techniques employed in current research. We conclude with some thoughts about future research directions. We also include some of our own research results, some of which are shown as examples.

Lossless compression of digital audio

Abstract: Lossless audio compression is likely to play an important part in music distribution over the Internet, DVD audio, digital audio archiving, and mixing. The article is a survey and a classification of the current state-of-the-art lossless audio compression algorithms. This study finds that lossless audio coders have reached a limit in what can be achieved for lossless compression of audio. It also describes a new lossless audio coder called AudioPak, which low algorithmic complexity and performs well or even better than most of the lossless audio coders that have been described in the literature.

Image restoration in astronomy: a Bayesian perspective

Abstract: When preparing an article on image restoration in astronomy, it is obvious that some topics have to be dropped to keep the work at reasonable length. We have decided to concentrate on image and noise models and on the algorithms to find the restoration. Topics like parameter estimation and stopping rules are also commented on. We start by describing the Bayesian paradigm and then proceed to study the noise and blur models used by the astronomical community. Then the prior models used to restore astronomical images are examined. We describe the algorithms used to find the restoration for the most common combinations of degradation and image models. Then we comment on important issues such as acceleration of algorithms, stopping rules, and parameter estimation. We also comment on the huge amount of information available to, and made available by, the astronomical community.

Electrical impedance tomography

Abstract: Electrical impedance tomography (EIT) is an imaging modality that estimates the electrical properties at the interior of an object from measurements made on its surface. Typically, currents are injected into the object through electrodes placed on its surface, and the resulting electrode voltages are measured. An appropriate set of current patterns, with each pattern specifying the value of the current for each electrode, is applied to the object, and a reconstruction algorithm uses knowledge of the applied current patterns and the measured electrode voltages to solve the inverse problem, computing the electrical conductivity and permittivity distributions in the object. This article focuses on the type of EIT called adaptive current tomography (ACT) in which currents are applied simultaneously to all the electrodes. A number of current patterns are applied, where each pattern defines the current for each electrode, and the subsequent electrode voltages are measured to generate the data required for image reconstruction. A ring of electrodes may be placed in a single plane around the object, to define a two-dimensional problem, or in several layers of such rings, to define a three-dimensional problem. The reconstruction problem is described and two algorithms are discussed, a one-step, two-dimensional (2-D) Newton-Raphson algorithm and a one-step, full three-dimensional (3-D) reconstructor. Results from experimental data are presented which illustrate the performance of the algorithms.

Joint audio-video object localization and tracking

Abstract: There has been a tremendous amount of research on object localization either involving microphone arrays or video cameras. Considerable less attention has been paid, however, to object localization and tracking based on joint audio-video processing thus far. This may be related to the lack of suitable algorithms for object localization simultaneously using multimicrophone outputs and color image sequences. In this article, we propose a solution to this problem. Before elaborating on joint audio-video processing, we review some previous work the areas of audio and video object localization. Then a recursive sensor fusion method based on decentralized Kalman filtering is introduced. Unfortunately, the decentralized Kalman filter cannot be directly used for joint audio-video object localization due to specific properties of the audio sensor. By properly adjusting the local audio position estimator, however, we manage to keep the overall architecture. We stress the general methodology.

Astronomical image and signal processing: looking at noise, information and scale

Abstract: We present methods used to measure the information in an astronomical image, in both a statistical and a deterministic way. We discuss the wavelet transform and noise modeling, and describe how to measure the information and the implications for object detection, filtering, and deconvolution. The perspectives opened up by the range of noise models, catering for a wide range of eventualities in physical science imagery and signals, and the new two-pronged but tightly coupled understanding of the concept of information have given rise to better quality results in applications such as noise filtering, deconvolution, compression, and object (feature) detection. We have illustrated some of these new results in this article. The theoretical foundations of our perspectives have been sketched out. The practical implications, too, are evident from the range of important signal processing problems which we can better address with this armoury of methods. The results described in this work are targeted at information and at relevance. While we have focused on experimental results in astronomical image and signal processing, the possibilities are apparent in many other application domains.

Creating a multiuser 3-D virtual environment

Abstract: For many years online text chat software such as ICQ has been used as a means of multiuser interaction. As higher bandwidth is available, multipoint videoconferencing systems such as NetMeeting or CUseeMe that allow people from different geographical locations to see and talk to each other are becoming popular. However, these videoconferencing systems lack the sense of immersion because each participant sees other participants in separate windows, and it is often difficult to tell who is talking to whom. Based on user study, Argyle and Dean (1965) suggested that during face-to-face communication people vary physical proximity, eye contact, and other behaviors to optimize an overall level of intimacy. In addition, Tang and Isaacs (1993) found that gaze awareness is important because participants can use the visual cue to determine when another participant is paying attention to them. These studies suggest that a more immersive way of multiuser communication is to connect the users in a three-dimensional (3-D) virtual environment so that users feel that they are communicating face to face. Moving from a text-based chat room environment to a 3-D environment creates new challenges in several areas such as computer animation, signal processing, and computer vision. We introduce immersive interactive technologies used in multiuser 3-D virtual environments. We also survey existing systems.

Face analysis and synthesis

Abstract: The author's goal is to generate a virtual space close to the real communication environment between network users or between humans and machines. There should be an avatar in cyberspace that projects the features of each user with a realistic texture-mapped face to generate facial expression and action controlled by a multimodal input signal. Users can also get a view in cyberspace through the avatar's eyes, so they can communicate with each other by gaze crossing. The face fitting tool from multi-view camera images is introduced to make a realistic three-dimensional (3-D) face model with texture and geometry very close to the original. This fitting tool is a GUI-based system using easy mouse operation to pick up each feature point on a face contour and the face parts, which can enable easy construction of a 3-D personal face model. When an avatar is speaking, the voice signal is essential in determining the mouth shape feature. Therefore, a real-time mouth shape control mechanism is proposed by using a neural network to convert speech parameters to lip shape parameters. This neural network can realize an interpolation between specific mouth shapes given as learning data. The emotional factor can sometimes be captured by speech parameters. This media conversion mechanism is described. For dynamic modeling of facial expression, a muscle structure constraint is introduced for making a facial expression naturally with few parameters. We also tried to obtain muscle parameters automatically from a local motion vector on the face calculated by the optical flow in a video sequence.

Automatic face cloning and animation using real-time facial feature tracking and speech acquisition

Abstract: We describe the components of the system used for real-time facial communication using a cloned head. We begin with describing the automatic face cloning using two orthogonal photographs of a person. The steps in this process are the face model matching and texture generation. After an introduction to the MPEG-4 parameters that we are using, we proceed with the explanation of the facial feature tracking using a video camera. The technique requires an initialization step and is further divided into mouth and eye tracking. These steps are explained in detail. We then explain the speech processing techniques used for real-time phoneme extraction and subsequent speech animation module. We conclude with the results and comments on the integration of the modules towards a complete system.

Imaging myocardial strain

Abstract: Measuring the local mechanical activity of the heart has lagged behind the measurement of electrical activity due to a lack of measurement tools. Myocardial wall motion abnormalities have been studied for years in the context of regional ischemia. Implanted beads and screws have been used to measure the mechanical activity of the heart in a few isolated regions. Over the past decade, precise and accurate methods for measuring local three-dimensional (3-D) myocardial motion with magnetic resonance imaging (MRI) have been developed using presaturation tagging patterns, velocity encoded phase maps, and displacement encoded phase maps. Concurrently, the quality of cardiac MRI images improved greatly with the use of customized receiver coils and the speed of acquisition has increased dramatically with the advent of undersampling techniques and new generations of MR machines with faster switching gradient coils. The use of these cardiac MRI techniques to produce an image of the local deformation of the heart in the form of a myocardial strain image is described. Using these images, the "mechanical activation" of the heart are defined, that is, the time of onset of contraction. A map of the mechanical activation over the heart is a direct analogy to an electrical activation map of the heart.

Developing a 2.5-D video avatar

Abstract: Immersive projection technology has become very popular as a virtual reality display system. A 2.5-D video avatar method was proposed and developed. The 2.5-D video avatar was created using a depth map generated by a stereo camera, and it was superimposed on the shared virtual world in real time. A 2.5-D video avatar was also transmitted between two immersive projection displays, computer augmented booth for image navigation (CABIN) and COSMOS, which were connected by a high bandwidth ATM network. In addition, we experimentally evaluated the accuracy of pointing when using the 2.5-D video avatar.

Multimedia ambiance communication

Abstract: The photo-realistic 3-D image space of multimedia ambiance communication offers enhanced interpersonal communication. Formed by taking the laws of perspective and the characteristics of human visual perception into account, the space provides a natural environment that users can feel to be a part of. It is based on the concept of a three-layer structure, with long-, mid-, and short-range views. We constructed a testbed for multimedia ambiance communication consisting of a high-speed graphics computer and a curved screen onto which images are stereoscopically projected from the rear, and developed a three-camera system for capturing environment images. In addition, we developed the two-plane expression for processing backdrop views and highly efficient mid-range views. Finally, we constructed a photo-realistic 3-D image space using these image processing techniques.

Transform coding: past, present, and future

Abstract: Reference LCAV-ARTICLE-2001-003doi:10.1109/MSP.2001.952801View record in Web of Science Record created on 2005-04-18, modified on 2017-05-12

Steps towards a virtual solar observatory

Abstract: We present three categories of sites from which solar data can be retrieved. We describe the retrieval software systems associated with these sites and then present software systems used for analyzing solar data. We show that both retrieval and analysis systems provide only limited global organization and/or standard access of data. We thus also discuss extensions to these systems, including data combination (or mapping) software, reusable software components, and visualization software. We argue that such extensions could eventually provide die level of software support expected by users.

Emerging medical imaging modalities

Abstract: This is the second issue of the Magazine to focus on a variety of medical imaging modalities. (The previous one was in January 1997.) The first issue contained articles on three standard modalities, magnetic resonance imaging (MRI), positron emission tomography (PET), and ultrasound, and one emerging modality, cardiac electrical imaging. This issue presents four emerging medical imaging modalities: electro/magnetoencephalography (E/MEG), electr ical impedance tomography (EIT), cardiac strain imaging, and diffuse optical tomography (DOT). E/MEG images brain function via sensor array measurement of the electrical and/or magnetic fields emitted by neural sources. EIT images the interior distribution of electrical impedance of various regions of the body by injecting current and measuring the consequent voltage at an array of electrodes. Cardiac strain imaging uses MRI tagging to image the mechanical motion and strain of the heart muscle, and DOT images the interior distribution of optical absorption and scattering in tissue by illuminating the tissue and measuring the light which emerges with an array of detectors. These modalities exhibit a wide diversity of properties which sample the range of medical imaging technologies. For instance, E/MEG images intrinsic sources, while the other three modalities use applied energy to image. E/MEG and EIT exploit essentially low-frequency phenomena, while MRI tagging and DOT use high-frequency energy. E/MEG is an explicitly functional imaging technique, as it directly images neural function. MRI tagging is explicitly anatomical, in the sense that it measures the time-varying mechanical properties of the cardiac muscle, although these properties are often a direct reflection of cardiac function. EIT and DOT are somewhat in between, as they image the physical location of tissue with differing electrical and optical properties, respectively; however Dana Brooks, Northeastern University

A proposal to minimize the NAAPIPT based on /spl mu/HRR

Abstract: Like the big pink gorilla waving you into the student car wash, the title of this article has the shameful purpose of attracting reader attention. The reader whose curiosity has been suffic ient ly piqued, however, will find that the puzzling title, unlike the gori l la , has a higher purpose. Please read on. The IEEE International Conference on Acoustics, Speech, and Signal Processing 2001 (ICASSP’01) was a superbly managed event which was technically and socially rewarding. The conference committee deserves the Signal Processing Society’s gratitude and commendation for a job well done. The outstanding quality of the conference notwithstanding, as ICASSP’01 progressed, it became increasingly clear to me that something deeply disturbing and extraordinarily counterproductive has insidiously crept into the way in which we present technical information at the world’s premiere SP conference. At ICASSP, many of us spend a few minutes each evening in our hotel rooms poring over the conference abstract booklet to set priorities for the following day. This year, to an extent greater than at any past ICASSP, I often found it difficult to determine the topic and significance of a paper by reading its title and abstract. At first I was inclined to blame my failure to understand on a lack of concentration due to the din of the trip-o-vision (defined by SPS member Dale Veenemann as the constant background of television programs that we never watch except while traveling). As hard as it is to accept one’s own weaknesses, I gradually began to realize that the problem was not one of acoustic background disturbances, but one of a personal failure to keep up with the current “developments” in my chosen profession. More precisely, I had to come to terms with the fact that I am A&AC (for the uninformed, that’s acronym and abbreviation challenged). I am certain that I am not alone in this experience, but for the common good, I am willing to publicly disclose my condition in the hope that others who are A&AC will benefit. The title of this article means (of course) “A Proposal to Minimize the Number of Acronyms and Abbreviations Present in ICASSP Paper Titles (NAAPIPT) Based on a Little Hotel-Room Research (μHRR).” The remainder of this article essentially comprises a plea to reverse the treacherous trend toward obfuscation embodied in the common acronym, backed up by extensive research that required vast numbers of minutes to undertake. We first explain the rationale for this research, then detail the methods and results, followed by discussion and conclusions.