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Visual information in 3D space has become the subject of much research in fields like 3D image communications and virtual reality. The huge amount of visual information in 3D space, however, makes the establishment of an efficient compression technique indispensable. In this regard, the authors have already proposed the concept of “space coding” that makes use of the redundancy in space itself, and have been investigating a specific coding technique that uses a multidimensional discrete cosine transform (DCT). In this paper, we extend this technique and propose a new coding technique that takes the structural characteristics of the object into account. To be more specific, we propose the concept of a “virtual object surface” as a technique for describing an object in structural terms taking compression rate into account, and attempt to improve coding efficiency with this technique. We also describe experiments performed to compare this technique with other techniques, and demonstrate the feasibility of the proposed technique on the basis of the results obtained. In addition, we examine a coding technique for performing high-speed image synthesis from compressed data. © 2001 Scripta Technica, Syst Comp Jpn, 32(12): 47–59, 2001 [ABSTRACT FROM AUTHOR]

In the field of 3D visual communications, a method of description of 3D images that would be neutral (independent) with respect to specific techniques for 3D input–output is desirable. In this context, the authors have proposed the concept of “ray-space” as a ray-based description method for 3D image data. In this paper, the concept of “ray-space” is employed to offer a new method for simultaneous description of 3D objects and space, as well as a technique for interactive manipulation in virtual space built using real images. Synthesis of images as seen from an arbitrary viewpoint in real space means extraction of ray data on a curved surface described by some basic formula in ray-space, using information about the viewpoint location. In this study, real-time processing is pursued; for this purpose, a reference table is employed for efficient extraction of ray data. Experiments were carried out concerning virtual manipulation of real objects in near-real time by means of overwriting ray-space data with ray data of the 3D object under consideration. The experiments confirmed that the proposed method offered efficient description of 3D space data and object manipulation. © 1999 Scripta Technica, Syst Comp Jpn, 30(14): 12–22, 1999 [ABSTRACT FROM AUTHOR]

This article relates to interactive command coding with active participation by the user in the coding process through his interactive operations, and structuralization of a moving image according to its substance. This coding process enables a low rate transmission with the preferential transmission of the substance of the original image, which is performed by using the user's interactive operations for extracting characteristics of objects relating to their shapes, texture, and motions, and by appropriately assigning a detailed description-based or simplified description-based technique, depending on the substance of the original image. In addition, it enables easy browsing for capturing outlines on the decoding side, and easy application even to nonlinear image editing, by modifying the motion-related parameters and also modifying the feature description technique to another technique. Concrete examples including test examples are given to explain this approach. © 1999 Scripta Technica, Syst Comp Jpn, 30(13): 73–83, 1999 [ABSTRACT FROM AUTHOR]

This paper presents a method for constructing a cyber-space with a high degree of reality by integrating the generation of images with an arbitrary viewpoint from the actually taken image, with the computer graphics (CG) techniques based on the geometric model. There are intensive studies of image-based rendering, which reproduces space based on actually taken images. This paper presents a new method that combines such a method and an existing geometric model, while maintaining the features of those techniques. In this paper, the ray space is used for the image-based rendering, and efforts are made to define the base plane so that the entire surroundings of the object can be observed. In order to represent the space with the mixed ray-space data and the geometric model, the same data structure as used in VRML is employed. © 1998 Scripta Technica, Syst Comp Jpn, 29(9): 21–31, 1998 [ABSTRACT FROM AUTHOR]

This paper proposes a new coding method using structural features such as shape and motion in a moving image so that they are described as plane motion in a 3D space. In this method, a layered representation (a moving image is described on a 2D projection plane) is extended by using a setting representation so as to handle 3D data. In the setting representation, 3D parameters which describe the orientation of a plane and the motion of a rigid body are needed for the regions that move coherently on the projection plane. Parameters can be estimated stably by applying a conventional 3D parameter estimation algorithm (which uses the square-error criterion based on the assumption of equal intensity between adjacent frames) to multiple frames. This paper also proposes a method of integration of the rigid-body motion of multiple regions so that the motion of images can be described more efficiently. The proposed method is compared with the layered representation using 2D data, and a conventional waveform-based method. The results show the effectiveness of the proposed method. © 1998 Scripta Technica, Syst Comp Jpn, 28(10): 50–59, 1997 [ABSTRACT FROM AUTHOR]

The human face includes a great deal of information related to individual features. If it were possible to describe facial images by means of parameters, one could think of a variety of applications. In this paper, wireframe models are applied to facial images, and orthogonal facial bases are found using principal-component analysis, while shape-related data and texture-related data are treated separately. By means of these facial bases, effective parametric description of facial images is achieved. The proposed method supports not only analysis of facial images but also image synthesis using obtained parameters. © 1998 Scripta Technica, Syst Comp Jpn, 28(10): 77–83, 1997 [ABSTRACT FROM AUTHOR]

To realize a user-friendly interface where a human and a computer can engage in face-to-face communication, the computer must be able to recognize the emotional state of the human by facial expressions, then synthesize and display a reasonable facial image in response. To describe this analysis and synthesis of facial expressions easily, the computer itself should have some kind of emotion model. By using a five-layered neural network which has generalization and superior nonlinear mapping performance, identity mapping training was performed using parameterized facial expressions. With respect to the space built in the middle layer of the five-layered neural network as an emotion model, emotion space was constructed. Based on this emotion space an attempt was made to build a system which can realize mapping from an expression to an emotion and from an emotion to an expression simultaneously. Moreover, to recognize a facial expression from the actual facial image of a human, the method of extracting the facial parameter from the facial points movement, is investigated. [ABSTRACT FROM AUTHOR]

This paper proposes a method which analyzes an expression from a facial image using a three-dimensional facial model and the extracts the facial expression. First, the head motion the action (such as those of eyebrows, eyes, and lips) are separated from the facial image. This is realized by estimating the three-dimensional facial and by compensating the motion. Next, the expression information is extracted from the separated facial actions in two ways. One is the method to extract successively the facial expressions considering the characteristics of the facial action actions based on the facial muscles. The other is the method to estimated the facial expression as a using the least-square method and regarding the facial actions by the facial muscles as a vector. Those methods are it possible to reconstruct the original expression from the extracted facial expression parameters. Finally, the result of the analysis of the facial expression from the actual image analysis of the facial result of evaluation by a psychologist to demonstrate the usefulness of the proposed method. The image reconstructed from the result of analysis also is compared with the original image. [ABSTRACT FROM AUTHOR]

If an object is a rigid body, it is possible to estimate its three-dimensional structure and motion mathematically from motion information. However, the assumption that objects are rigid bodies includes a disadvantage that it is not stable against noise and that the circumstance of application is restricted. When considering application to natural images or modeling of vision, a general-purpose method for estimating three-dimensional structure and motion which allows discrepancy from rigid bodies is desired. Thus, in this piper, an algorithm is presented for estimating three- dimensional structure and motion incrementally from a Long image sequence using the condition for "smoothness of motion" instead of the rigid body assumption. That is, as a constraint, a physical property is used whereby an object generally performs smooth motion due to inertia and elasticity. Formulating this condition, i.e., smoothness of motion as a stabilizing function for regularization, the three-dimensional information is estimated incrementally so that it is suitable to an input image and motion is motion. By considering smoothness of motion, three-dimensional information of each frame can be stored incrementally, and thus a flexible algorithm that is robust and also applies to the motion of a nonrigid body is obtained. Furthermore, by presenting the results when applying this method to the motion of rigid and nonrigid bodies, the robustness of this method against noise and flexibility is shown which also applies to nonrigid bodies. [ABSTRACT FROM AUTHOR]

Model-based image coding has been highlighted recently as a high-efficiency coding method for TV telephone and TV conference systems. In a model-based coding system, an ultralow-rate image transmission is realized by obtaining common models of a facial image at both sides of a communication and by transmitting only modification parameters between them. However, it is difficult to realize a realtime processing of a model-based coding with a conventional iterative-processing type computer since the amount of material to analyze and synthesize at both sides is very large. Realtime processing is absolutely necessary to realize a practical system using this method, i.e., high-speed processings at both the transmitter and receiver are required. This paper describes a realtime facial image synthesis method based on a multiprocessor construction with a transputer. The transputer is a microcomputer having a communication capability with multiple processors and 10 MIPS CPU performance. Using this system in a pipeline processing with 20 processors, it is possible to synthesize realtime facial images at a rate of about 16 frames per second. If only a part around the lips is transmitted, it is possible to synthesize an image at a rate of about 40 frames per second with a network using five processors. [ABSTRACT FROM AUTHOR]

Video communications play an important role in an information-oriented society. A cost-effective image coding technique capable of rendering high quality video communication services is an important component of any information system. This paper describes an algorithm for image sequence coding using three-dimension- al (3-D) structure and motion information. Each image is treated as a 2-D projection of a 3-D object, with 3-D information derived and used in the coding scheme. Since the coding scheme considers physical 3-D in- formation, it provides data compression at the transmitter and improved image quality at the receiver. Furthermore, because the image is represented in a structure-oriented fashion, it lends itself to image recognition and image understanding. This aids in the realization of high quality communication systems. The proposed algorithm makes extensive use of 3-D structure and motion information in conjunction with 3-D motion interpolation and 3-D motion compensation predictive coding technique to achieve efficient, high quality image sequence coding. A method is described that has 3-D structure and motion information extraction, and an incremental scheme is presented for stable estimation of 3-D structure and motion information of rigid as well as non-rigid bodies. [ABSTRACT FROM AUTHOR]

A facial motion image synthesis method for intelligent man-machine interface is examined. Here, the intelligent man-machine interface is a kind of friendly man-machine interface with voices and pictures in which human faces appear on a screen and answer questions, compared to the currently existing user interfaces which primarily uses letters. Thus what appears on the screen is human faces, and if speech mannerisms and facial expressions are natural, then the interactions with the machine are similar to those with actual human beings. To implement such an intelligent man-machine interface it is necessary to synthesize natural facial expressions on the screen. This paper investigates a method to synthesize facial motion images based on given information on text and emotion, The proposed method utilizes the analysis-synthesis image coding method. It constructs facial images by assigning intensity data to the parameters of a 3-dimensional (3-D) model matching the person in question. Moreover, it synthesizes facial expressions by modifying the 3-D model according to the predetermined set of rules based on the input phonemes and emotion, and also synthesizes reasonably natural facial images. [ABSTRACT FROM AUTHOR]

Generally speaking, it is necessary to extract knowledge from an expert in a given discipline and implement this knowledge into a system when constructing an expert system. However, it is not easy to extract knowledge in such fields as medical diagnosis or pattern recognition because the inference logic depends on the experience and intuition of the expert. This paper proposes an automatic rule extraction mechanism using statistical analysis. In this system, production rules are expressed in the form of the threshold function. Because the threshold function can describe any kinds of inference logic, it is expressed easily as a linear combination of input vectors and weighting coefficients. Thus weighting coefficients can be calculated by the same method as a discriminant function. If only one threshold is defined, general Boolean logic an be expressed. Moreover, an ambiguous inference rule can be expressed when the threshold levels are multidefined and a membership function is defined at each category. Further, the Fuzzy Tree Search algorithm which combines ambiguous inference and tree search is proposed at the end of this paper. This algorithm can search and determine an optimum cluster with little calculation and good performance. In practice, a medical diagnostic system applied to psychiatry which has most ambiguous diagnostic logic, has been constructed based on this algorithm and inference rules have been extracted automatically. By this experiment, Fuzzy Tree Search is as fast as the tree search technique and has as good a performance as a full search clustering technique. [ABSTRACT FROM AUTHOR]