中口 俊哉

In this article, we propose an efficient and accurate compressive-sensing-based method for estimating the light transport characteristics of real-world scenes. Although compressive sensing allows the efficient estimation of a high-dimensional signal with a sparse or near-to-sparse representation from a small number of samples, the computational cost of the compressive sensing in estimating the light transport characteristics is relatively high. Moreover, these methods require a relatively smaller number of images than other techniques although they still need 500-1000 images to estimate an accurate light transport matrix. Precomputed compressive sensing improves the performance of the compressive sensing by providing an appropriate initial state. This improvement is achieved in two steps: 1) pseudo-single-pixel projection by multiline projection and 2) regularized orthogonal matching pursuit (ROMP) with initial signal. With these two steps, we can estimate the light transport characteristics more accurately, much faster, and with a lesser number of images. (C) 2011 The Japan Society of Applied Physics

Endoscopic image of the tubular organs is recorded as discontinuous shots taken from a fixed angle without 3D or objective information. Presentation of a 3D picture of intraluminal cavity of the tubular organ covering whole-range of observation from continuous endoscopic video frames would be effective for the diagnosis and identification of the lesion, as well as offering intuitive information to the patients. In this paper, a new method for processing virtual endoscopy from "actual" endoscopic video images is proposed to observe the internal structures of tubular organs. The method consists of two steps of processing: 1. the panoramic image is processed from video image of endoscopy or the tubular organs where the endoscope was pulled at a constant speed automatically using a stepper motor or manually by a doctor. 2. the 3D-height information was extracted from a panoramic image using the intensity of the pixel based on the inverse-square low. This method is carried out under the assumption that the same part of the organ has similar property of reflection and the endoscope is the only source of illumination inside the body. The extracted height information will correspond with the distance between the point of the object and the endoscope. Finally, the virtual tubular object is reconstructed with the panoramic image texture. This method makes use of the advantages of conventional virtual endoscopy processed from "actual" endoscopic images, affording intuitive, multi-angle observation of the objects with color information and fine resolution. To date, virtual endoscopic images have been successfully processed from endoscopic video files for the colon, esophagus, ureter, and the urethra. Such images offer sharing of intuitive information for doctors and patients, and are promising in improving the accuracy of diagnosing the lesions.

We propose a method for surface reconstruction of artist paintings. In order to reproduce the appearance of a painting, including color, surface texture, and glossiness, it is essential to acquire the pixel-wise light reflection property and orientation of the surface and render an image under an arbitrary lighting condition. A photometric approach is used to estimate bidirectional reflectance distribution functions (BRDFs) and surface normals from a set of images photographed by a fixed camera with sparsely distributed point light sources. A robust and computationally less expensive nonlinear optimization algorithm is proposed that optimizes the small number of parameters to simultaneously determine all of the specular BRDF, diffuse albedo, and surface normal. The proposed method can be applied to moderately glossy surfaces without separating captured images into diffuse and specular reflections beforehand. Experiments were conducted using oil paintings with different sur-face glossiness. The effectiveness of the proposed method is validated by comparing captured and rendered images. (C) 2011 SPIE and IS&T. [DOI: 10.1117/1.3533329]

Purpose Kampo medicine (Japanese traditional herbal medicine) can identify "Mibyou" (disease-oriented state) based on visual tongue inspection by a trained physician. Surface colors of uncoated tongue provide essential features. A hyperspectral imaging system which performs regional image analysis of the tongue color spectrum was developed to automatically inspect the uncoated tongue. Methods Hyperspectral tongue surface images were acquired by a camera equipped with an integrating sphere. The color spectrum from 4 tongue areas-uncoated tongue, coated tongue, lip, and perioral areas-were quantified. The average spectrum of each area was determined and 4 images calculated by focusing on the differences between respective spectra; highlight, shadow, tongue coat, and lip-weighted images were calculated. The uncoated tongue area was extracted by subtraction. Results Reproducibility was evaluated by applying the camera and extraction algorithm to 44 images from human subjects. Eighty-two percentage were judged as acceptable by a Kampo medicine physician expert. Conclusions Using a hyperspectral camera and extraction algorithm, the tongue color of the uncoated part was automatically extracted. This technique is suitable for tongue color analysis and may help non-trained users to identify "Mibyou".

In the present article we analyze the relationship between ambient illuminations and psychological effects while viewing still images displayed on a liquid crystal display (LCD). In two experiments, six kinds of images were displayed on the LCD under different brightness of illumination conditions and were rated by 15 observers, and four kinds of images were displayed under different colors of illumination conditions and were rated by 27 observers. The semantic differential method and factor analysis method are introduced to analyze the subjective evaluation. It is shown that comfort in viewing is enhanced according to the increase in brightness of the ambient illumination. Particularly, realistic sensation and dynamism are enhanced while retaining comfort with the illumination behind the LCD. It is also shown that realistic sensation and dynamism and comfort are enhanced under the illumination of average chromaticity of displayed images. (C) 2011 Society for Imaging Science and Technology. [DOI: 10.2352/J.ImagingSci.Technol.2011.55.1.010502]

A fundamental study was conducted to analyze the requirements for appropriately reproducing the appearance of gold leaf on print without metallic inks in cases where accurate colorimetric matching is not possible because of the large difference in the luminance range. Based on the pixel-wise bidirectional reflectance distribution functions (BRDFs) and surface normals of a gold leaf sample (a sheet of gold leaf pasted on a sheet of Japanese paper) , a wide variety of print reproductions under different geometric conditions of image rendering and luminance compression were created using computer graphics. A visual experiment was carried out where the observers evaluated the reproducibility of the appearance of the original gold leaf sample on the prints. The results of this visual experiment show that the requirements possibly include the following: (1) spatial change in brightness (or lightness) in the gold leaf region should be apparent through control over geometric conditions for image rendering, (2) the brightest area in the gold leaf may not necessarily be as bright as the print gamut, and (3) the darkest area in the gold leaf should be sufficiently dark when compared with the brightest area.

We characterize sheets of white paper using three bidirectional reflectance distribution function (BRDF) model parameters estimated from the BRDF in the specular reflection plane. The radiance factors of eight types of paper sheets having a wide range of material characteristics were measured for 284 geometries in the specular reflection plane. They were approximated within an average error of 4.5% using a linear combination of Torrance-Sparrow and Lambert's BRDF models. The proposed model well approximated the BRDF of samples in the specular plane. Based on the estimated BRDF model parameters, the eight measured paper sheets could be broadly classified into glossy papers and rough papers. The two glossy papers were distinguishable from each other, while the six rough papers could be classified into three groups using the BRDF model parameters. The proposed method is considered to be effective for characterizing a wide range of white paper ranging from glossy to matte paper. (C) 2010 Society for Imaging Science and Technology. [DOI: 10.2352/J.ImagingSci.Technol.2010.54.6.060503]

Despite their usability advantages over traditional authentication systems, biometrics-based authentication systems suffer from inherent privacy violation and non-revocability issues. In order to address these issues, the concept of cancelable biometrics was introduced as a means of generating multiple, revocable, and noninvertible identities from true biometric templates. Apart from BioHashing, which is a two-factor cancelable biometrics technique based on mixing a set of tokenized user-specific random numbers with biometric features, cancelable biometrics techniques usually cannot preserve the recognition accuracy achieved using the unprotected biometric systems. However, as the employed token can be lost, shared, or stolen, BioHashing suffers from the same issues associated with token-based authentication systems. In this paper, a reliable tokenless cancelable biometrics scheme, referred to as BioEncoding, for protecting Iris Codes is presented. Unlike BioHashing, BioEncoding can be used as a one-factor authentication scheme that relies only on sole Iris Codes. A unique noninvertible compact bit-string, referred to as BioCode, is randomly derived from a true Iris Code. Rather than the true Iris Code, the derived BioCode can be used efficiently to verify the user identity without degrading the recognition accuracy obtained using original Iris Codes. Additionally, BioEncoding satisfies all the requirements of the cancelable biometrics construct. The performance of BioEncoding is compared with the performance of BioHashing in the stolen-token scenario and the experimental results show the superiority of the proposed method over BioHashing-based techniques.

Many super-resolution methods have been proposed to enhance the spatial resolution of images by using iteration and multiple input images. In a previous paper, we proposed the example-based super-resolution method to enhance an image through pixel-based texton substitution to reduce the computational cost. In this method, however, we only considered the enhancement of a texture image. In this study, we modified this texton substitution method for a hybrid camera to reduce the required bandwidth of a high-resolution video camera. We applied our algorithm to pairs of high- and low-spatiotemporal-resolution videos, which were synthesized to simulate a hybrid camera. The result showed that the fine detail of the low-resolution video can be reproduced compared with bicubic interpolation and the required bandwidth could be reduced to about 1/5 in a video camera. It was also shown that the peak signal-to-noise ratios (PSNRs) of the images improved by about 6 dB in a trained frame and by 1.0-1.5 dB in a test frame, as determined by comparison with the processed image using bicubic interpolation, and the average PSNRs were higher than those obtained by the well-known Freeman's patch-based super-resolution method. Compared with that of the Freeman's patch-based super-resolution method, the computational time of our method was reduced to almost 1/10.

Due to the development and popularization of high-definition televisions, digital video cameras, Blu-ray discs, digital broadcasting, IP television and so on, it plays an important role to identify and quantify video quality degradations. In this paper, we propose SV-CIELAB which is an objective video quality assessment (VQA) method using a spatio-velocity contrast sensitivity function (SV-CSF). In SV-CIELAB, motion information in videos is effectively utilized for filtering unnecessary information in the spatial frequency domain. As the filter to apply videos, we used the SV-CSF. It is a modulation transfer function of the human visual system, and consists of the relationship among contrast sensitivities, spatial frequencies and velocities of perceived stimuli. In the filtering process, the SV-CSF cannot be directly applied in the spatial frequency domain because spatial coordinate information is required when using velocity information. For filtering by the SV-CSF, we obtain video frames separated in spatial frequency domain. By using velocity information, the separated frames with limited spatial frequencies are weighted by contrast sensitivities in the SV-CSF model. In SV-CIELAB, the criteria are obtained by calculating image differences between filtered original and distorted videos. For the validation of SV-CIELAB, subjective evaluation experiments were conducted. The subjective experimental results were compared with SV-CIELAB and the conventional VQA methods such as CIELAB color difference, Spatial-CIELAB, signal to noise ratio and so on. From the experimental results, it was shown that SV-CIELAB is a more efficient VQA method than the conventional methods.

The aim of this work is to develop an efficient medical image segmentation technique by fitting a nonlinear shape model with pre-segmented images In this technique. the kernel principle component analysis (KPCA) is used to capture the shape variations and to build the nonlinear shape model The pre-segmentation is carried out by classifying the image pixels according to the high level texture features extracted using the over-complete wavelet packet decomposition Additionally, the model fitting is completed using the particle swarm optimization technique (NO) to adapt the model parameters The proposed technique is fully automated is talented to deal with complex shape variations. can efficiently optimize die model to it the new cases, and is robust to noise and occlusion In this paper. we demonstrate the proposed technique by implementing it to the liver segmentation front computed tomography (CT) scans and the obtained results are very hopeful.

本論文では，CIECAM02を用いた照明環境下におけるプロジェクタ投影画像の画質改善手法について述べる．プロジェクタは暗室環境下での利用が一般的ではあるが，近年の小型化・可搬性の向上により，屋外や展示会場などでも活用されはじめている．照明された環境下では，明るい光源をプロジェクタに用いることで文字情報は認識可能である．しかし，画像を投影する場合はコントラストの低下や色度のズレにより，暗室下のような再現が困難となる．そこで本研究では，周囲環境光変化の視覚的な影響を考慮した投影画像の画質改善手法を開発した．提案手法では，カメラを用いてプロジェクタ投影面の三刺激値を計測したのち，その三刺激値に順応した場合の反対色応答と明るさ応答をCIECAM02から算出する．そして，照明された環境下での反対色応答とコントラストを暗室下での見えに近づける補正を行うことにより，画質改善を行った．両眼隔壁を用いた一対比較法による主観評価実験を行い，有効性を確認した．<br>

We propose a practical and simple measurement function of three dimensional (3D) length for endoscopy based on triangulation using manually pointed correspondences. This system is a novel combination of conventional methods. 3D length information is useful for many medical purposes and the burden of manual procedures can be reduced by focusing on length. We employed a novel combination for length measurement, that is, a monocular endoscope with an electromagnetic tracking sensor. The proposed method can measure the length without any equipment for light projection and changing the current procedure of endoscopy. Our method is made more robust and reliable than the automatic correspondence techniques through the best use of the expertise of endoscopists. We developed a prototype system and evaluated its accuracy. From experimental results, we showed that the proposed method can measure the 3D length of static objects accurately as long as the measurement geometry is suitable.

An irregular contour of the medial femoral condyle (MFC) on magnetic resonance imaging (MRI) appears to indicate the severity of medial-type knee osteoarthritis (OA). The purpose of this study was to establish a system to enable objective assessments of OA knee severity using newly developed software that semi-automatically measures irregularity of the MFC. (1) We evaluated 48 patients aged 50-83 years with 55 knees of medial-type OA. The following scores were recorded: Lysholm score, visual analogue scale (VAS) and the Japanese Knee Osteoarthritis Measure (JKOM). MFC irregularity was automatically calculated by newly programmed computer software. Four parameters for condyle irregularity were calculated: (a) the average thickness of the contour (ATC), (b) the ratio of the upper surface length to the lower surface length of the contour (RUL), (c) average squared thickness of the contour (ASTC) and (d) standard deviation of the contour thickness (SDC). (2) Nine knees that underwent total knee arthroplasty were further analysed histopathologically and compared with irregularity score. Statistically, the RUL and SDC were significantly correlated with the Lysholm score, VAS and JKOM, with good reliability. Histological examinations showed that an irregular contour reflected the density of cystic lesions formed in subchondral bone. An irregularity of MFC on MRI is correlated with OA disease severity clinically and histopathologically. The new computer software is useful to objectively assess OA disease severity.

Photorealistic image synthesis is a challenging topic in computer graphics. Image-based techniques for capturing and reproducing the appearance of real scenes have received a great deal of attention. A long measurement time and a large amount of memory are required in order to acquire an image-based relightable dataset, i.e., light transport or reflectance field. Several approaches have been proposed with the goal of efficiently acquiring light transport [Sen et al. 2005 Fuchs et al. 2007]. However, since, with the exception of the recently proposed compressive sensing method [Peers et al. 2009], most previous studies have focused on scene adaptive sampling algorithms, conventional methods cannot perform efficiently in the case of a scene that has significant global illumination. In this paper, we present a non-adaptive sampling method for measuring light transport of a scene based on separation of the direct and global illumination components.

In this research, the authors have developed a compact and fast measurement system for three-dimensional (3D) shape, normal vector, and bidirectional reflectance distribution function (BRDF) of a 3D object, e.g., a human face. Since the proposed system uses linear light sources and a luminous intensity distribution of these light sources, the BRDF can be measured for a short time and without large measurement space. The proposed system is evaluated by two methods whereby the authors confirmed its accuracy: by measuring sample known objects and by comparing actual and reproduced images. (C) 2009 Society for Imaging Science and Technology. [DOI: 10.2352/J.ImagingSci.Technol.2009.53.6.060501]

The histomorphologic and passive biomechanical properties were studied in the mid-colon of 16 non-diabetic and 20 streptozotocin (STZ)-induced diabetic rats (50 mg/kg STZ, ip). The diabetic rats were divided into groups living 4 and 8 weeks after the induction of diabetes (n = 10 for each group). The mechanical test was a ramp distension of fluid into the colon in vitro. The colon diameter and length were obtained from digitized images of the segments at pre-selected pressures and at the no-load and zero-stress states. Circumferential and longitudinal stresses and strains were computed from the length, diameter, and pressure data and from the zero-stress state geometry. The blood glucose level increased 3-4-fold in the diabetic rats compared with the controls (P < 0.001). Diabetes generated pronounced increases in the colon weight per length, wall thickness, and wall cross-sectional area (P < 0.001). Histologically, the thickness of all layers was increased during diabetes (P < 0.05), especially the mucosa layer. The opening angle, and absolute values of residual strain increased in the diabetic group (P < 0.05 and P < 0.01, respectively). Furthermore, diabetes increased the circumferential and longitudinal stiffness of the colon wall (P < 0.001). The observed changes in residual strain, opening angle, and stress-strain relation may be contributing factors to colonic dysfunction and abdominal pain in diabetic patients.

A method is proposed to analyze the preferred Modulation Transfer Function (MTF) of printing medium like paper for the image quality of printing. First, the spectral intensity distribution of printed image is simulated by changing the MTF of medium. Next. the simulated image is displayed on a high-precision LCD to reproduce the appearance of printed image. An observer rating evaluation experiment is carried out to the displayed image to discuss what the preferred MTF is. The appearance simulation of printed image was conducted cell particular printing conditions: several contents; ink colors, a halftoning method and a print resolution (dpi). The experiments oil different, printing conditions earl be conducted since our simulation method is flexible about changing; conditions.

This paper presents a deformable hollow organ model considering the self-collision between the inner surfaces of a hollow organ for real-time surgical simulation. The hollow organ was modeled by the finite element method with 10400 tetrahedral elements, 2160 nodes, and 1040 inner meshes. In the model, the continuous collision detection is performed between the inner surfaces to prevent penetrations of them. As a result, it was shown that the model is well-behaved about 40 fps by a standard PC with Pentium4 3GHz and 2GB RAM. © 2009 SPIE.

The block based motion estimation technique is adopted by various video coding standards to reduce the temporal redundancy in video sequences. The core of that technique is the search algorithm implemented to find the location of the best matched block. Indeed, the full search algorithm is the most straightforward and optimal but computationally demanding search algorithm. Consequently, many fast and suboptimal search algorithms have been proposed. Reduction of the number of location being searched is the approach used to decrease the computational load of full search. In this paper, hybridization between an adaptive search algorithm and the full search algorithm is proposed. The adaptive search algorithm benefits from the correlation within spatial and temporal adjacent blocks. At the same time, a feature domain based matching criteria is used to reduce the complexity resulting from applying the pixel based conventional criteria. It is shown that the proposed algorithm produces good quality performance and requires less computational time compared with popular block matching algorithms.

Ulcerative colitis (UC) is associated with intestinal and extra intestinal clinical manifestations. The profound organic changes in UC indicate that the colonic mechanical and mechanosensory functions are affected. The aim was to study acute morphological and biomechanical properties of the distal colon in oxazolone-induced UC in BALB/C mice. Six normal male BALB/C mice and 10 oxazolone-induced UC mice were studied. UC was induced by epicutaneous and intrarectal administration of oxazolone. The mechanical test was done as a distension experiment where the colon was distended up to 20 cmH(2)O. The pressure, outer diameter and length were recorded simultaneously. Circumferential and longitudinal stresses and strains were computed. The intestinal specimens were processed for histology. The mucosa was infiltrated with acute and chronic inflammatory cells. Mucosal bleeding, irregular ulcers crypt abscess, and destruction of the epithelial border were observed. Although, the mucosa in ulcers was much thinner than in the normal controls, the mucosa and submucosa around the ulcer were thicker than in the normal controls (P<0.05). Oxazolone-induced colitis increased the circumferences and wall cross-sectional area (P<0.01), the opening angle and residual strain at the serosa increased (P<0.01). Furthermore, the circumferential and longitudinal stiffness increased in the UC wall and was most pronounced in longitudinal direction. The opening angle and residual strain was linearly correlated to the wall thickness, area and inflammation degree. In conclusion, morphological and biomechanical changes of the colon occurred during the development of UC. The increased stiffness may contribute to the abnormal function in patients with UC. (C) 2009 Elsevier Ltd. All rights reserved.

In the National Museum of Japanese History, 215,759 artifacts are stored and used for research and exhibitions. In museums, due to the limitation of space in the galleries, a guidance system is required to satisfy visitors' needs and to enhance their understanding of the artifacts. We introduce one exhibition using imaging technology to improve visitors' understanding of a kimono ( traditional Japanese clothing) exhibition. In the imaging technology introduced, one data projector, one display with touch panel interface, and magnifiers were used as exhibition tools together with a real kimono. The validity of this exhibition method was confirmed by results from a visitors' interview survey. Second, to further develop the interactive guidance system, an augmented reality system that consisted of cooperation between the projector and a digital video camera was also examined. A white paper board in the observer's hand was used as a projection screen and also as an interface to control the images projected on the board. The basic performance of the proposed system was confirmed; however continuous development was necessary for applying the system to actual exhibitions. (C) 2009 SPIE and IS&T. [DOI: 10.1117/1.3267085]

Estimating the noise level of a digital image is important for many applications such as noise removal, image quality assessment, and so on. For practical use in these applications, the estimation method should be achieved from a single image. Ce <i>et al.</i> developed a single image noise estimation method. In their method, <i>a priori</i> information of noise characteristics was generated by the computer simulation and used in Bayesian MAP. However, they did not consider the inherent characteristics of each camera, depressing the estimation accuracy. Therefore, in this paper, we take into account the inherent characteristics of a camera by using camera specific <i>a priori</i> in Bayesian MAP. Camera specific <i>a priori</i> is constructed from preliminarily measurements of the camera instead of a computer simulation. The experimental results show the improved accuracy of noise estimation.

本稿では，デジタルカメラの RGB 画像から，任意照明光下における 被写体の測色値を予測する手法を提案する． 3 バンドカメラによる撮影では，測色値の異なる複数の分光反射率が 同一のセンサ応答を与え得る． そのため，センサ応答から正確な測色値への変換は一対多関係となり，一意に決定することができない． 提案手法では，被写体と同じ材質の物体が有する分光反射率の統計的特徴を 参照することにより，与えられたセンサ応答から最も期待度の 高い測色値を導出する．

第一報では，デジタルカメラの RGB 画像から任意照明光下における 被写体の測色値を予測する手法を提案した． 第二報となる本稿では，提案手法の評価について述べる． シミュレーションによる評価では，提案手法の予測精度を，照明光，カメラの分光感度，被写体の種別，および色予測モデル構築に 使用する母集団データの複数の組み合わせについて検証した． その結果，精度，および母集団データの選択に対する安定性のいずれについても，従来手法に対する提案手法の優位性が確認された． また，デジタルカメラで撮影して得た画像を用いた実験により，提案手法は実際の画像に対しても有効であることが示された．

我々は製造段階での作業に対する質感の変化を視覚的にシミュレーションする質感再現システムを開発している.目標とするシステムには作業と連動する質感再現が重要で,実作業,特に手動作との連携が必要不可欠である.そこで本研究では机上作業における手の位置と動作をロバストに計測する手法を開発した.手の位置の検出には赤外線のみを発するプロジェクタで投影した構造パターンを用い,机上から一定高さ以内の手の位置のみを検出することで,作業時のみの手の位置を検出することができる.また手動作判定に必要な手の形状計測には空間コード化法を用いたが,計測範囲を計算で求めた手の周辺位置のみと限定することで計測及び形状再構築の処理時間を飛躍的に削減することができた.本報告ではこれら画像処理的な手法と,試作したプロトタイプシステムの性能について述べる.

In percutaneous puncture simulation, the finite element method is usually used to compute the needle bend and tissue deformation. This method, however, tends to be not suitable for real-time applications such as training systems due to its high computational cost. In this paper, we propose a novel deformable model with a low computational cost. The proposed model reproduces needle bend and tissue deformation in the direction perpendicular to the long axis of the needle. The proposed model consists of a soft tissue deformation model based on the Long Element Method (LEM) and a needle bending model which is designed to be consistent with the tissue model. The parameters for both models are put in the same simultaneous equation to be solved for the simulation. We verified that the proposed model shows a low computational cost by the computer simulation. The accuracy of the model was also evaluated by the experiment using needles and tissue phantoms. The experimental result using only needles showed that a bend could be estimated by the pre-optimized parameters. The optimized parameters were available even if different displacement was given to the manipulated point of the needle.

This paper proposes a practical measurement system for bidirectional reflectance distribution functions (BRDFs) of a three-dimensional (3D) object with a linear light source. Using the linear light source, the proposed system can reduce the number of image acquisitions which are necessary for an estimation of the spatially-varying BRDFs of the object. Furthermore, the size of the proposed system is much smaller than a conventional system which uses a parallel light. In this proposed system, the light field of the linear light source is previously measured to determine direction and radiance of incident rays to each point of the object, because the direction and radiance are not constant at each point. Using the proposed system, the BRDF of a point of flat objects was experimentally measured, and results showed validation of the estimation accuracy of the proposed system. Measurement efficiency of the proposed system was also evaluated by comparing reflectance model parameters estimated by the conventional and proposed systems. For the estimation, the reflectance function of a 3D object was measured by both systems. The estimation accuracy of the proposed method was also evaluated by comparing among a real image and rendered 3D objects of the conventional and proposed methods. (c) 2008 The Optical Society of Japan.

A simple regression-based model of skin diffuse reflectance is developed based on reflectance samples calculated by Monte Carlo simulation of light transport in a two-layered skin model. This reflectance model includes the values of spectral reflectance in the visible spectra for Japanese women. The modified Lambert Beer law holds in the proposed model with a modified mean free path length in non-linear density space. The averaged RMS and maximum errors of the proposed model were 1.1 and 3.1%, respectively, in the above range. (C) 2008 The Optical Society of Japan

In this article, a video-based analysis for facial skin appearance with an automatic face tracking technique is proposed. The change of skin appearance under various illuminations observed by illuminating the face from various light source positions, and the changes in facial appearance are recorded (is a video stream during this measurement. The recorded video stream is then analyzed to obtain the bidirectional reflectance distribution function (BRDF) (it each position of the facial skin. Automatic face tracking is necessary to compensate the facial movement in order to obtain an accurate BRDF measurement at each position. Since conventional face tracking techniques cannot be used for a face illuminated from various light source positions, a new face tracking technique that is robust to the various face shadings has been developed. Experimental studies show the effectiveness of both the proposed video-based analysis technique and the automatic face tracking technique. (c) 2008 Wiley Periodicals, Inc. Cot Res Appl, 33, 477-484, 2008: Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20440

我々は, 被写体の顔の位置, 向き, 口の動きを1台のカメラで実時間追跡することにより化粧シミュレーションを実現するバーチャルミラーシステムを構築した. バーチャルミラーとは, ハーフミラーとビデオカメラを用いることで, ディスプレイを被写体 (今回の場合は使用者の顔) への画像処理が可能な鏡として扱うシステムである. このシステムを顔追跡, 顔への付加処理と組み合わせることで, 簡便な化粧シミュレータを構築した. 顔追跡には, 顔の動きと表情を分離して確率的に推定する手法を提案した. また, 追跡に必要なデータは人体寸法のデータベースより取得した. これにより1台のカメラでも精度良く顔追跡を行うことが可能となった.

液晶ディスプレイ(LCD)やプラズマディスプレイ(PDP)等様々な種類の平面ディスプレイが急速に普及しており,それらの画質を評価・比較するために定量的評価法が盛んに研究されている.MPRT (Moving Picture Response Time)は平面ディスプレイの動きぼやけを定量化する方法の一つであり,応答時間に代わるLCDの動画表示性能を示す指標として注目されている.通常のMPRT評価法は水平方向の動きぼやけのみしか計測していないが,動きぼやけは水平方向に限らず様々な方向に独立して存在する.この論文では,ロボットアームを用いたMPRT計測システムを構築することで,水平方向を含む様々な方向に対して動きぼやけを計測することを可能にした.計測の際様々なデバイス間でMPRTを比較するために,PDPの表示特性を考慮した計測法の改良を行っている.また様々な方向に対して知覚される動きぼやけを評価する主観評価実験を行い,計測によって得られたMPRTと比較することで水平方向以外の動きぼやけ評価の必要性を論じる.

We examined the validity of perceived blur edge width (PBEW) by analyzing the correlation between observer rating values and physical properties that were extended blur edge width (EBEW) and PBEW. We also examined the correlation with changing contrast sensitivity function (CSF) models in the calculation of PBEW. In our results, PBEW correlated more with the observer's rating values than EBEW. It was also shown that Spatio-Velocity CSF model is significant for calculating PBEW.

Many methods have been proposed to restore the blurred images caused by motion blur, camera shake, out of focus and so on. However, little work has been done to restore the blurred images by multiple factors. In this paper, we propose a method for restoration of blurred image by camera shake and characteristics of system response.

An interactive animation method for viscoelastic materials builds on Rouse's spring-bead model. Particles are connected one-dimensionally by spring forces to represent single polymer chains. The method approximates the collision's force between particles through the particle density's gradient. This model lets the viscoelasticity be changed dynamically by severing the interconnection of polymer chains.

腹腔鏡下手術において、先端部に二つのカメラを配置した立体腹腔鏡を用いてステレオ視を行い、臓器の形状を計測する手法がStoyanovらにより提案されている。Stoyanovらの手法では、画像全体を同時に対応付け、臓器の形状を復元した。しかし、計算コストが高く、リアルタイム処理を実現できなかった。そこで本研究では、画像全体ではなく、画像の局所部毎に別々に対応付けを行うことで計算コストを削減し、よりリアルタイム処理に適した処理を実現する。形状が既知である物体を撮影した画像を用いて、計算コスト及び復元精度について、従来手法との比較を行った。その結果、提案手法が従来手法と同等の精度を維持しつつ、計算コストが大幅に削減されたことから、提案手法の有効性を確認した。(著者抄録)

We propose a technique for estimating gene expression values for duplicated data on cDNA microarrays. In the scatter plots, the distribution is constructed from a mixture of normal two-dimensional distributions, which represent fluctuations in gene expression values due to noise. An expectation-maximization (EM) algorithm is used for estimating the modeling parameters. The probability that duplicated data is shifted by noise is calculated using Bayesian estimation. Six data sets of rice cDNA microarray assays were used to test the proposed technique. Genes in the data sets were subjected to clustering based on probability of true value. Clustering successfully identified candidate genes regulated by circadian rhythms in rice. (c) 2007 The Optical Society of Japan

The authors have developed a multi-spectral scanner for accurately printing proofs that employs an LED array coupled witha photodiode array to measure the reflectance spectra. The system is composed of an LED array with five different spectral radiant distributions and 2048 silicon photodiodes with a Selfoc lens array (SLA) for imaging. Five types of LED were selected from among 40 types of commercially available LED with different spectral radiant distributions in order to minimize the average color difference Delta E-94 between the measured and estimate reflectance spectra of 81 typical color color charts. The multiple regression method based on the clustering and polynomial regression algorithm was introduced for highly accurate estimation of the spectral reflectance for printing. The results indicate that the average and maximum color differences Delta E-94 between the measured and estimated reflectance spectra of 928 color charts were 1.02 and 2.84, respectively. The scanner can measure the reflectance of prints having a 0.5 mm pitch resolution and a scanning speed of 100 mm/s. The field programmable gate array (FPGA) and digital signal processor (DSP) were introduced in order to accelerate the calculation of sensor calibration and the estimation of the reflectance spectra of printed proof for practical and commercial use. As a result, the developed scanner could measure the reflectance spectra of printed proof within 20 s. (c) 2007 Society for Imaging Science and Technology.