We present non-photorealistic rendering techniques that depict the motion of 3D rigid objects in a still image extracted from a 3D animation sequence. In order to represent fast moving 3D objects in a still image, the motion blur technique has been employed. However, it is too expensive to render various kinds of motions in real time. Several non-photorealistic rendering approaches have been proposed to represent motions of 3D objects using “speed lines”. To draw speed lines, vertices of 3D object contours on a projected screen plane are detected from several frames. They are connected and drawn along motion tracks of 3D objects. However, users are required to select “speed line” types suited to motion speed of the objects manually and repeatedly. We propose non-photorealistic rendering techniques that depict various kinds of motion of 3D objects automatically and in real time. To realize these techniques, first, a combined motion is decomposed into a translation motion of the center of gravity of the object and its rotational motion, and then each motion is depicted. Experimental results verify our technique is effective enough to depict automatically various motions of 3D objects in real time.

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We analyze the electromagnetic wave scattering problem from the Holographic Fourier Grating. This analysis is treated as a two-dimensional problem in the scalar boundary value. In the analytically procedure, T-matrix method based extinction theorem by Huygens' principle and Green's theorem is applied. This formulation is also useful because T-matrix element is presented by the analytical form for the Bessel function series. Numerical examples are showed for diffraction efficiencies in which the incident angle and the profile of Fourier grating are variable.

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Subjective staircase illusion is a well-known visual illusional phenomenon in psycho-physical field. It is the phenomenon in which 3D staircase is observed, when a tilted dot matrix pattern is watched binocularly from the horizontal direction. Although the results based on the subject experiments in psychology field were reported until now, the detailed 3D staircase's structure and the mathematical relations between observational conditions and the staircase's structure such as the number of steps etc were not clear. Then, we verified it through the computer experiment of our binocular vision computational model which imitates man's binocular vision. As a result, we could check that a staircase illusion occurs computationally by applying the psychological hypothesis called “Nearest Neighbor Rule” when both eyes have some convergence. Consequently, we could formulate the generating mechanism of the 3D staircase illusion, and clarify the detailed staircase's 3D structure and the relation between observational conditions and staircase's structure, which were not analyzed in the conventional subject experiment using human beings.

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Recently, several digital watermarking techniques have been proposed for hiding data in the frequency domain of image signals. However, little attention has been given to the optimal position in the frequency domain for embedding watermarks. We have attempted to improve the performance of both the extraction of watermarks and the quality on an image after compressed by JPEG technique by creating a multicriteria optimization problem for deciding the positions of watermarks in the frequency domain and obtaining an approximately optimum solution to this problem. The approximately optimum solution is obtained using the genetic algorithm. The experimental results show that the proposed method generates watermarked images of good quality and high tolerance to JPEG compression. In addition, the improvement of security has been achieved using the characteristic secret key to embed and extract watermark information. The reported method with the wavelet transforms is used to embed and extract watermark information.

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IrSimple is a high-speed Infrared communications protocol to provide simple and instant wireless communications between mobile devices and digital home appliances. This paper provides a mathematical model with which we derive a simple equation for IrSimple throughput efficiency. Based on this model, we compare the performance of IrSimple protocol with the existing IrDA protocol for exchanging digital contents at high data rates. Results are presented which reveal that IrSimple protocol scales well for use with high data rates compared to the existing OBEX protocol. The significance of parameters such as IrSMP block size and link minimum turnaround time on IrSimple performance is also examined. Furthermore, an enhancement of existing error control scheme to provide robustness for IrSimple protocol at high bit error rates and an improvement in flow control to reduce redundant data retransmissions are presented. Finally we investigate the robustness of our proposed flow control scheme for all possible cases where frame losses can occur due to transmission error.

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A method for facial expression recognition for a speaker was proposed using thermal image processing. We reported that we got the average recognition accuracy of 90% for one speaker, when she exhibited one of the intentional facial expressions of “angry”, “happy”, “neutral”, “sad”, and “surprise”. In this study, we improved our system to be able to save thermal static images automatically at the times decided to recognize facial expression for a speaker with or without glasses. In this method, the above five kinds of facial expressions were discriminable with the average recognition accuracy of 88% for seven speakers. Then, we analyzed the influences of individual variations on facial expression recognition.

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A method to simulate projected images that audience will actually watch in mesopic vision case and a visibility evaluation method for projected slides are proposed. The former method is based on actual luminous efficiency functions of cone cells and rod cells in human retina in photopic and scotopic situations. The latter method is based on some digital image processing techniques.

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[in Japanese]

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