Showing papers by "Yoichi Miyake published in 2000"

System design for accurately estimating the spectral reflectance of art paintings

Abstract: Accurately estimating the spectral reflectance of art paintings from low-dimensional multichannel images requires that both image-acquisition hardware with appropriate spectral characteristics and appropriate estimation software be applied to the captured multichannel image. In this study, a system that incorporates both factors is designed and developed on the basis of the minimum-mean-square error criterion. The accuracy of spectral estimation by use of this system is evaluated, and the system's high performance is demonstrated.

Independent Component Analysis of Spectral Absorbance Image in Human Skin

Abstract: The image of spectral absorbance in human skin is analyzed by independent component analysis. The spectral absorbance image is estimated from an image with red, green, and blue channels. The qualitative information and spatial distribution of the pigments can be extracted by the independent component analysis. It is shown that the extracted absorption characteristics of the pigments are corresponding to those of hemoglobin and melanin.

Mapping Pigmentation in Human Skin by Multi-Visible-Spectral Imaging by Inverse Optical Scattering Technique.

Abstract: Mapping pigmentation in human skin is expected to give useful information in reproducing and diagnosing various skin colors. In this research, maps of melanin, oxyhemoglobin and deoxy-hemoglobin in skin are estimated from multi-visible-spectral image by using an inverse optical scattering technique. In the inverse optical scattering technique, first of all, a forward model of optical scattering is build to simulate the spectral reflectance of skin. Changing the variable parameters in the forward model, the simulation is repeated until the simulated spectral reflectance matches with the spectral reflectance at each pixel of the multi-spectral image. The principle of the proposed estimation technique was confirmed by imaging the human forearm under the venous occlusion, the venous and arterial occlusion, and by imaging a slapped region of the human forearm.

Development of a multispectral camera system

Abstract: A highly accurate multispectral camera and the application software have been developed as a practical system to capture digital images of the artworks stored in galleries and museums. Instead of recording color data in the conventional three RGB primary colors, the newly developed camera and the software carry out a pixel-wise estimation of spectral reflectance, the color data specific to the object, to enable the practical multispectral imaging. In order to realize the accurate multispectral imaging, the dynamic range of the camera is set to 14 bits or over and the output bits to 14 bits so as to allow capturing even when the difference in light quantity between the each channel is large. Further, a small-size rotary color filter was simultaneously developed to keep the camera to a practical size. We have developed software capable of selecting the optimum combination of color filters available in the market. Using this software, n types of color filter can be selected from m types of color filter giving a minimum Euclidean distance or minimum color difference in CIELAB color space between actual and estimated spectral reflectance as to 147 types of oil paint samples.

Alternative Oblique-Incidence Reflectometry for Measuring Tissue Optical Properties

Abstract: To deduce the optical properties, the absorption coefficient SmUaand reduced scattering coefficient μ’s, of turbid medium, Lin et al. (Appl. Opt. 34 (1995) 2362) proposed an oblique incidence reflectometry in which the diffusion approximation was assumed. In this paper we propose an alternative method which does not assume the diffusion approximation but uses a Monte Carlo light propagation model. Two features are extracted from the diffuse reflectance distribution detected on the medium surface, and optical properties are then estimated by looking up the predetermined table generated by Monte Carlo simulations. The validity of the proposed method has been confirmed by computer simulations.

An evaluation of image quality for hardcopy based on the MTF of paper

Abstract: Image quality of hardcopy is significantly influenced by paper properties. In this article, two kinds of image, a hardcopy and an image projected onto paper, are analyzed using a function based on the Modulation Transfer Function (MTF) of paper, and evaluated by observer rating experiments. As a result, good correlation was obtained between the function values and the observer rating values. It is shown experimentally that the reflectance and MTF of paper are of significant importance in the image quality of hardcopy.

Evaluation of sharpness and graininess in digital imaging system and its application to improve total image quality

Abstract: Techniques to evaluate image quality are necessary. However, several problems to be investigated still remain in the evaluation of the image quality. Though it is difficult to evaluate the image quality totally, the sharpness and graininess are focused on as components of total image quality. As examples of the evaluation and improvement of image quality, two experimental results are shown in this paper. At fist, the outline and remarks in the evaluation of image quality are described. Then experimental results about evaluation of multi-level error diffusion images and improvement of noisy images without sharpness degradation are presented. Finally future problems and the conclusions are addressed.