Toshihiro TOYOTA
Verified @pref.shizuoka.lg.jp
Lighting and Acoustic Division
Industrial Research Institute of Shizuoka Prefecture
RESEARCH, TEACHING, or OTHER INTERESTS
Industrial and Manufacturing Engineering
Scopus Publications
Scopus Publications
K Käläntär, Tomonori Tashiro, Toshihiro Toyota, and Yasuki Yamauchi
Wiley
In this paper we study the metrology issues of non‐planar light sources (NPLSs). We use near‐field (NF) goniometric measurement method to characterize the NPLSs. By using the NF method, we obtain the luminance image, the intensity, the spectra and the color of the source as a function of the ray angle, i.e., the zenith and azimuth angles in spherical coordinate system. The NF light rays are used to obtain the characteristics of the light source at far‐fields by post processing. The results of the NPLS metrology and the features of the NF goniometric measurement system are reported.
Shunsuke Kohko, Miyoshi Ayama, Michico Iwata, Nobuhiro Kyoto, and Toshihiro Toyota
Illuminating Engineering Society of Japan
At present, there is no internationally accepted method of evaluation that converts discomfort glare in pedestrian zones into numerical form. While LED streetlights are rapidly coming into wide use, their lightemitting parts are often nonuniform in luminance compared with streetlights that employ HID lamps. This nonuniformity has been noted as a factor responsible for the emergence of glare. A subjective evaluation experiment was conducted with seven types of streetlights placed in an outdoor field that simulated a pedestrian zone. The streetlights used for the experiment were selected in consideration of the type of light source and the luminance uniformity of the light-emitting surfaces. The results showed that luminancebased photometric quantities are a better measure of discomfort glare than is the illuminance at the observer’s eye for light sources with both uniform and nonuniform surfaces. Based on the experimental results, a new evaluation equation that converts discomfort glare in pedestrian zones is proposed.
Toshihiro Toyota and Shigeki Nakauchi
Springer Science and Business Media LLC
Ken-Ichi Kobayashi, Masaaki Mori, Ken Nishino, Toshihiro Toyota, and Shigeki Nakauchi
SAGE Publications
Food quality is strongly affected by its components and their spatial distributions. Recently, spectroscopic methods have been widely applied as a non-destructive and rapid method to measure food quality. Although it is a versatile technique, the measurement system is extremely costly for practical use. In this paper, we propose a simple measurement system using a small set of band-pass filters. A food constituent was predicted using output from the band-pass filters as input for a multiple linear regression model, and the bands were designed to obtain high prediction accuracy characterised by the determination coefficient, using hyperspectral data by the optimisation approach. We designed three sets of filters to separately determine contents such as oleic acid, total unsaturated fatty acid and fat content in raw beef using NIR hyperspectral data, and then we implemented these designs as real optical filters. By mounting the filter in front of the lens of an NIR monochrome camera, we captured a set of filtered images. We then performed a pixel-by-pixel prediction of the content to enable the spatial distribution to be visualised. The determination coefficient ( R2) and prediction error, which we characterised by the root mean square error of cross-validation ( RMSECV), of this filtering method ( R2 = 0.638–0.739, RMSECV = 3.13–5.15) were superior to those obtained with partial least squares (PLS) regression using hyperspectral measurements ( R 2 = 0.610–0.643, RMSECV= 3.70–6.12). Our method, therefore, facilitates the application of a hyperspectral technique for practical use.
Ken-Ichi Kobayashi, Yasunori Matsui, Yosuke Maebuchi, Toshihiro Toyota, and Shigeki Nakauchi
SAGE Publications
The meat quality grade of a beef carcass is greatly affected by its visible fat content. In premium beef from Japanese Black (Wagyu) cattle, a high fat content is greatly valued. However, the fatty acid composition, which is linked to the properties of the fat, is not considered in grading. In this paper, we describe the feasibility of an evaluation method based on food composition and its distribution. An intact raw beef cut from Wagyu cattle was used as an evaluation target. A total of 90 samples from various parts of three Wagyu cattle were measured by near infrared (NIR) hyperspectral imaging at wavelengths of 1000–2300 nm at a spatial resolution of 380 urn pixel−1 and were also analysed by conventional physical and chemical methods. The fat and fatty acid content were selected as the objective content, including the proportions of total saturated fatty acid (SFA), total unsaturated fatty acid (UFA) and the main fatty acids: myristic [C14:0, where C x: y indicates the number of carbon atoms ( x) and the number of double bonds ( y)], palmitic (C16:0), stearic (C18:0), myristoleic (C14:1), palmitoleic (C16:1), oleic (C18:1) and linoleic (C18:2). The mean spectrum from an area extracted from the hyperspectral image to fit the area analysed by physical and chemical methods was used to develop partial least squares regression models for prediction of fat and fatty acid content. The prediction of total fat, SFA and UFA were satisfactory with r2, standard error of prediction ( SEP) and ratio of prediction to deviation ( RPD) values of 0.90, 0.87 and 0.89, 4.81%, 1.69% and 3.41% and 2.84, 2.43 and 2.84, respectively. For individual fatty acids, the r2 and RPD values ranged from 0.68 to 0.89 and 1.69 to 2.85, respectively. Prediction of fat content for each pixel of the hyperspectral image made using these prediction models yielded spatially distributed visualisations of the content. These results showed the feasibility of a beef evaluation method based on fat content evaluated by NIR hyperspectral imaging.
Toshihiro Toyota, Shigeki Nakauchi, and Shiro Usui
Institute of Image Information and Television Engineers
The relationship between the statistical properties of a color signal and the conditions for perceptual color transparency was investigated. First, we investigated the physical change in color statistics by overlapping transparent color filters. The transparent color filters shifted the average of color signal and reduced its variance. Moreover, the color and luminance signals were highly correlated. A transparent field was perceived in the simulated scenes which consist of color noise with similar statistical changes caused by transparent color filters. We also performed a psychophysical experiment to investigate what effect color statistics have on surface segregation. The results suggest that second order statistics (correlation) is used in the visual system as one of the cues for perceptual color transparency.