[in Japanese]

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Daylight simulation problem is a difficult problem in computer graphics due to the complexity of daylight itself. Based on the purposes of simplifying the traditional simulation process and improving the realism at the same time, this paper proposes an image-based daylight simulation method in which color temperature is used to describe daylight. This method can simulates various daylights at different color temperature realistically by using only one general image. The main idea of this approach is using a spectra database, called SOCS, to generate a spectral reflectance image from a general image. The experimental results illustrate the efficiency of this approach.

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Color-information representation by using a uniform color space in terms of human JNDs (just-noticeable differences) is important in many industrial situations as well as in image processing, visually loss-less image coding, and noise evaluation. In this paper, we describe a new method for building a non-linear color space, which makes use of various JND data sets. We evaluated our algorithm by computer simulation and found that the color space obtained by the algorithm was superior to that obtained by conventional methods in terms of uniformity and representation compactness.

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Color matching of automotive interiors is of importance in a total quality look. Our color measurement system helps to eliminate human errors in the judgements of color difference. The purpose of our study was to develop a new measurement system that has the visual sensibility of the human eye. In this paper, we discribe a new formula for measuring the color difference of plastic parts with a grained leather pattern on the surface. In our study, we found that the currently used color-difference formula does not correspond to the actual visual impressions. Our new measurement system was developed by using a gonio colorimeter instead of an integrating sphere colorimeter and correcting the colorimetric data based on the visual sensibility extracted from our psychophysical experiments. Our system shows good correlation with human visual judgments and it was found to be accurate in the tests.

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[in Japanese]

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[in Japanese]

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We investigated the basic white-light optical process for the reconstruction of encoded color holographic images by using liquid crystal display (LCD) panels. Instead of using three lasers, we used a metal halide lamp as the only white-light source. The lamp had good characteristics in each band of the wavelengths of the color components. Light components neaded for the reconstruction of images were extracted by color separation using dichroic mirrors, and then, color stereographic images were reconstructed by composing the lights filtered out by a hologram pattern formed on the LCD panels through prisms. As a result, several fine color stereographic images were reconstructed in our optical system equipped with a white-light source and LCD panels.

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Recently several new WDM/SCM optical transmission systems have been developed, to enable a higher transmission capacity of access networks such as CATV. Analog transmission performance of optical amplifiers and optical filters is important for these systems. Yet, there have been few studies that addressed this issue. In this paper, the required performance of optical devices and a system design method are investigated. In our study, we focused on the technical issues essential for 10, 000-channel WDM/SCM (32 WDM×310 ch SCM) systems using cost-effective direct modulation schemes. First, the mechanisms of sub-carrier level variation and distortion generation caused by FM-AM conversion on optical filters were examined both theoretically and experimentally. The required bandwidth of optical filters suitable for these systems was calculated. We then estimated the optical distribution number depending on the optical signal power input into EDFAs. We found that a configuration using three cascaded EDFAs enables developing 10, 000-channel WDM/SCM systems with 8, 000 distributions.

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A variable neutral-density filter using guest-host liquid crystal devices was fabricated for color video image sensing. The liquid crystal devices contain black dichroic dyes whose absorption is controlled by voltage applied to the device. The filter keeps the spectral balance of transmitted light almost constant for three primary color wavelength regions, even when its transmittance is changed. The fabricated filter exhibited a high extinction ratio of 70 : 1 for an applied voltage of 20 V_rms, and the color temperature shift of the transmitted light was less than 200 K. We then developed an automatic light exposure system in which the variable filter is driven so that the video signal level is kept constant. By applying aperture control of a zoom lens to this automatic exposure system, we were able to achieve a new video effect where the focal depth of a captured image could be independently controlled while keeping the video level constant.

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An artificial retina (AR) LSI with a highly accurate on-sensor-image projection function was developed. The fabricated 32×32-pixel AR LSI compresses 1024 bytes of input image data to 64 bytes of projection data on the focal plane. It can also modulate projection data into spatial and temporal differential data that fit motion-detection algorithms. The AR LSI has a high sensitivity of 20 V/1x·sec and a wide dynamic range of 66 dB, which enables high-speed motion detection. As a result, the AR LSI, even through a combination with an 8-bit microcontroller, makes it possible to build a motion-detection system that outputs motion data for a high speed motion corresponding to a 200-μs time difference at a high report rate. This proves the effectiveness of the hierarchical processing structure consisting of a processing function of the AR LSI and a recognition function of the microcontroller.

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Synthesing of hair images is one of the most important and challenging computer-graphics problems.In this paper, we describe a new technique for automatically generating a realistic human-hair texture on 3 D models of human characters. This research was inspired by the similarity between the texture of human hair and the texture generated by an LIC algorithm. The developed of hair technique generates hair with a texture of human hair by using a vector field defining the directions of hair strands as the input to the 3 D LIC algorithm.

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Receivers used for digital broadcasting, which provides many channels and services, will be more sophisticated than conventional receivers. This additional functionality may permit or may require new types of remote controls to be used. To investigate the conditions under which remote control devices are easy to operate, we performed remote controls operation tests with elderly subjects in a GUI environment. The results of this subjective evaluation showed that the elderly people preferred trackball remote controls to conventional remote controls with buttons. By analyzing the operating time and observing the subjects' operation of four types of remote controls, we found that subjects tended to prefer those controls : which they could use without having to look down, and for which there was a significant learning effect within a relatively short period.
It was clear that even elderly users could adapt easily to novel devices under such conditions.

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The performance of serially concatenated turbo coding systems using various RLL codes was evaluated and compared with that of PRML systems in a perpendicular magnetic recording channel. The error rates of these systems were experimentally estimated by an actual R/W channel using a spinstand with a double-layered perpendicular magnestic recording medium. The experimental results show that among the PRML systems, PR1ML, PR2ML, and E²PR3ML had good performance. We also found that our turbo coding system using a PR2 system had the best performance among all RLL-coded serially concatenated turbo coding systems we investigated. A 64/65 (0, 8) code was found suitable for our turbo coding system.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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