Electronics and Communications in Japan (Part III: Fundamental Electronic Science)最新文献

In sensor networks, many of the sensor nodes are often positioned in clusters, and there is a correlation between the data obtained at the various sensor nodes by observation. This kind of observational data is collected at fusion centers. In this paper, we study the observation precision at fusion centers from the viewpoint of the Kullback–Leibler (KL) information. In particular, we consider transmission path errors arising when transmission is made from each sensor node via wireless communication paths, as a factor in the deterioration of the KL information, or in other words, observation precision, and study its effects and methods for reducing it. In this paper, we study the KL information obtained in fusion centers when there have been transmission path errors in cases where the correlation between observational data is all equal, and where the correlation is random. We show that the deterioration of the KL information can be reduced in fusion centers by using the correlation of observational data in the estimates of error data. In addition, we present examples of estimating the correlation between observational data in fusion centers that use correlation, and of estimating error data using correlation. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(11): 1–10, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20250

In the use of the three-dimensional data obtained from a stereo system, laser range finder, and other equipment, merge processing is important. This paper proposes a new merge method for range images, based on the volume-based technique. In the proposed method, in contrast to the conventional method, the voxels are adaptively segmented according to the curvature of the surface shape to be reconstructed. This helps to represent the geometrical shape efficiently, effectively utilizing the computation resources. In the framework of the proposed merge process, additional features such as color and the laser reflectivity can be added to the three-dimensional geometrical information, which helps to maintain sharp edges in the texture and to perform rendering and the texture mapping effectively. By examining the consensus for both the geometrical shape and the color in the whole framework, the merge is made robust to noise. In this paper, the system is described first, and then the results of application to several kinds of actual data are presented. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(11): 50–60, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20353

Median filters and other nonlinear filters have been investigated for restoration of degraded images with Poisson noise. Recently, subband image restoration using the wavelet transform has been attracting much attention. This method is effective for small-amplitude noise, but in the case of Poisson noise, large-amplitude noise exceeds the preset threshold and is not removed. In this study, we propose a new method of noise removal from degraded images with Poisson noise by using a combination of the M-transformation [5] and the wavelet BayesShrink method. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(11): 11–20, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20357

There has recently been much discussion of MPLS multicast approaches. MMT and BLAST-Cast have been proposed as means of establishing multicast LSP using unicast LSP. These techniques are useful not only as transfer techniques in introducing the MPLS multicast technique, but also for the deployment of MPLS multicasting in established MPLS networks, since the scale can be expanded stepwise, and the cost of deployment and operation can be reduced in the deployment of MPLS multicast in established MPLS networks. However, there have been few studies of the detailed signaling protocol to be used in such an approach, or of problems accompanying these techniques. Consequently, we investigated a signaling protocol that can be applied to these approaches, and devised an MPLS multicast mechanism using RSVP-TE. The proposed mechanism was implemented and evaluated. This paper discusses the design and implementation of the proposed mechanism, together with its evaluation. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(11): 40–49, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20354

There is a need for methods to display 3-dimensional data (volume data) obtained from such procedures as computer tomography (CT), magnetic resonance imaging (MRI), and 3-dimensional radar in a form that can easily be interpreted by humans. Methods that present such data via a 3-dimensional display are able to show the 3-dimensional image directly to humans and are well adapted to allow the recognition of 3-dimensional structure. In particular, 3-dimensional displays using holography are especially suited to assisting humans in interpreting 3-dimensional information. In this paper we propose a volume rendering computer-generated hologram (CGH) method that calculates a hologram directly from volume data using CGH technology without employing any intermediary images or photographic procedures. Since in this method the hologram is generated computationally, there is significant flexibility in how the 3-dimensional image can be displayed. As well as enabling images to be displayed with shading, a whole range of different 3-dimensional display techniques are possible; for example, at one extreme we can display only the surfaces in the volume data making the internal regions opaque, while by introducing transparency we can make the internal structures visible. We have confirmed the effectiveness of the proposed method by using it to create computer-generated holograms on the basis of 3-dimensional medical MRI data and conducting optical experiments. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(11): 31–39, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20355

In this paper the authors propose a data hiding method for JPEG images that has a degree of freedom in selecting the hiding position and does not require a reference image or knowledge of the hiding position during extraction. In conventional methods, the position for the transform coefficients which hide the data must be specified beforehand, and that position must be known during extraction. The proposed method does not require specifying the hiding position beforehand and offers some freedom in selecting the hiding position. Therefore, a hiding position that is appropriate can be selected for each image and block to be subjected to JPEG encoding. Given this, the proposed method can reduce image degradation and improve compression efficiency compared to the conventional methods. Moreover, because knowledge of the hiding position is not required during extraction, information management is thus simpler during extraction. The effectiveness of the proposed method is confirmed through simulations. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(11): 21–30, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20356