Spectral reflectance in human skin tissue has been studied through Monte Carlo simulation using the nine-layered skin tissue model. It is important to estimate the penetration depth of detected light affected by absorption and scattering to know the condition of human skin. In this study, we estimated the depth of penetration of photons in the visible wavelength range that propagate inside skin tissue and are detected at different positions in the vicinity of the illuminated area by using Monte Carlo simulation.
We have developed a system that separates and measures the optical properties of skin, i.e., the surface reflection, diffuse reflection, and sub-surface scattering components of the skin. This system includes two polarization filters that separate light from the skin into a surface reflection component image and a diffuse reflection component image. Furthermore, by using a projector as a light source and irradiating the skin using a high-frequency binary illumination pattern, the sub-surface scattering component image alone can be separated and generated. Using the proposed system, we performed a survey of 154 Japanese women aged from their 20s to their 70s and analyzed age-related changes in the optical properties of their skin. The results revealed the following. First, the luminance value Y of the surface reflection from the cheek and its standard deviation within the analysis area increase with age. Second, the Y value of diffuse reflection from the skin decreases with age. Third, the amount of light in the sub-surface scattering components also decreases with age. The proposed system is expected to have a wide range of applications in the medical and cosmetic fields.
Similarity in skin reflectance spectra with different combination of absorption and scattering conditions makes erroneous estimation of parameters for any measured spectrum through the database containing simulated spectra. In this study, such similar reflectance spectra are investigated by Monte Carlo simulation and phantom experiment.
Spectral reflectance in human skin tissue has been studied through Monte Carlo simulation using the Nine-layered skin tissue model. It is important to estimate absorption and scattering parameters of human skin tissue to know the condition of human skin. In this study, we investigated a method for estimating the absorption and scattering parameters by considering the effect of specific layers on the spectral band in the spectral reflectance database of human skin generated by Monte Carlo simulation.
To measure optically physiological condition inside skin tissue, it is important to estimate optical parameters in skin tissue. In this study, we investigated a method to estimate absorption and scattering parameters in skin tissue from the spectral reflectance database constructed by using Monte Carlo simulation with a nine-layered skin tissue model.
Skin spectral reflectance can be used for estimate optical properties of human skin tissue, but there is a potential problem. We investigated skin conditions producing similar reflectance spectra but different point spread functions of reflected intensity on the skin surface in the framework of Monte Carlo simulation.
We have developed so far the method for imaging simultaneously blood flow and blood concentration change in skin tissue by using two-wavelength near infrared laser speckle patterns. We conducted experiments for human volunteers to confirm the feasibility of the method for estimating temporal response in the blood flow and blood concentration change in a human finger to occlusion on a human arm with different pressures from 50 to 150 mmHg. The results demonstrated that the response may depend on individual minimum and maximum blood pressure values.
Human skin surface has unevennesses called sulcus cutis and crista cutis. It is known that these affect the light propagation in
human skin. In this study, we made a prototype of skin tissue phantom and investigated its spectral properties and problems
to be solved.
We have developed the method for imaging blood flow and blood concentration change by using laser speckle in fiber
illumination. We experimentally discuss the relationship of blood occlusion condition and individual response of blood
concentration change measured by the method.
Light propagation into human skin tissue is studied by using Monte Carlo simulation (MCS) with the multi-layered skin tissue model. In this study, we analyzed light propagation in various internal conditions of skin tissue by calculating photon fluence based on Monte Carlo simulation. And we examined a method for quantitative evaluation on the depth and spread of light propagation in skin tissue.
Skin surface texture has an influence on light propagation in tissue and changes the impression of the skin appearance. We use Monte Carlo simulation for estimating spectral reflectance in human skin. However, the simulation was made for parallel layered model having a flat surface. In this study, we investigated to use texture-added skin model in the simulation. We confirmed that a change of intensity distribution was found when the skin surface texture was changed.
KEYWORDS: Color reproduction, Skin, RGB color model, Reflectivity, Monte Carlo methods, CCD cameras, Error analysis, Databases, Color difference, Blood
Skin measurements based on spectral reflectance are widely studied in the fields of medical care and cosmetics. It has the advantage that several skin properties can be estimated in the non-invasive and non-contacting manner. In this study, we demonstrate the color reproduction of human skin by spectral reflectance using RGB images and the Wiener estimation method.
There are sulcus cutis and crista cutis on human skin surface. It is known that these affect the light propagation in human skin. To investigate it experimentally, it is desirable to reproduce sulcus cutis and crista cutis in skin tissue phantom. In this study, we made a prototype of skin tissue phantom having a shape of sulcus cutis and crista cutis, and investigated its optical properties and problems to be solved.
To perform a contactless plethysmographic imaging, we investigated a method to estimate the concentrations of
oxygenated and deoxygenated blood in human skin tissue from RGB images, based on the Monte Carlo simulation.
We propose a method to visualize the arterial inflow, the vascular resistance, and the venous capacitance in the skin tissue from red, green, blue (RGB) digital color images. The arterial inflow and the venous capacitance in the skin tissue are visualized based on an increase in the rate of change in the total blood concentration and the change of the total blood concentration during upper limb occlusion at a pressure of 50 mmHg. The resultant arterial inflow with the measured mean arterial pressure also provides an image of the vascular resistance in human skin. The arterial inflow, the vascular resistance, and the venous capacitance acquired by the method are well correlated with those obtained from the conventional strain-gauge plethysmograph. The correlation coefficients R between the estimated values by the method and the measurements by the SPG are calculated to be 0.83 (P<0.001) for the arterial inflow, 0.77 (P<0.01) for the vascular resistance, and 0.77 (P<0.01) for the venous capacitance. The arterial inflow and the venous capacitance in the skin tissue are significantly higher in active subjects compared with the sedentary subjects, whereas the vascular resistance was significantly lower in the active subjects compared with the sedentary subjects. The results of the present study indicate the possibility of using the proposed method for evaluating the peripheral vascular functions in human skin.
In order to visualize human skin hemodynamics, we investigated a method that is specifically developed for the visualization of concentrations of oxygenated blood, deoxygenated blood, and melanin in skin tissue from digital RGB color images. Images of total blood concentration and oxygen saturation can also be reconstructed from the results of oxygenated and deoxygenated blood. Experiments using tissue-like agar gel phantoms demonstrated the ability of the developed method to quantitatively visualize the transition from an oxygenated blood to a deoxygenated blood in dermis. In vivo imaging of the chromophore concentrations and tissue oxygen saturation in the skin of the human hand are performed for 14 subjects during upper limb occlusion at 50 and 250 mm Hg. The response of the total blood concentration in the skin acquired by this method and forearm volume changes obtained from the conventional strain-gauge plethysmograph were comparable during the upper arm occlusion at pressures of both 50 and 250 mm Hg. The results presented in the present paper indicate the possibility of visualizing the hemodynamics of subsurface skin tissue.
This paper presents experimental studies on diffuse reflectance spectra of blood in cylindrical glass vessels embedded in the Intralipid solution as a skin tissue model, and also f human skin surfaces. The measured spectra are mainly governed by the absorption characteristics of a small amount of blood added into the Intralipid medium. To evaluate quantitatively diffuse reflectance spectra, we employed the color perception on the basis of the CIE x-y chromaticity diagram. Results for the skin tissue model were found to coincide with those for veins in the human skin tissue.
The bluish appearance of veins in the skin tissue was experimentally investigated by in vivo and in vitro measurements. The color of skin surface including veins inside was evaluated by spectrophotometry and color analysis in the CIEXYZ and CIELAB colorimetric systems. The bluish appearance was successfully interpreted by the dominant wavelength and the color difference. Results for in vitro experiments showed that the degree of bluish appearance depends on the depth and diameter of blood vessels.
The feature analysis of the conventional exchange format used in the field of the graphic arts is performed. It becomes clear from this consideration that most standard defining the transmission format have too strict limitations to adapt for the communication required in the creative and flexible work.
The database AMPAC proposes the simple and unified format to describe single parameter of whole field of design, production and management. The database described by the format can be used commonly in any field connected by the network production system, since the description accepts any parameter in any fields and is field independent definition.
This paper investigates spectral reflectance of blood vessels in a skin tissue phantom. Measured reflectance spectra are slightly influenced by the vessel diameter, depth from the surface, and oxygen saturation state. We discuss a possibility of extracting the information on blood vessels from the reflectance spectra on the basis of color perception using the dominant wavelength in the CIE xy chromaticity diagram with the pseudo-reference white. The results show the usefulness of this method.
This paper experimentally studies the diffuse reflectance spectra of blood in cylindrical glass vessels embedded in the Intralipid solution as a skin tissue phantom. The measured spectra were mainly governed by the absorption characteristics of a small amount of blood added into the medium, but were also slightly influenced by the vessel diameter, depth from the surface, and oxygen saturation state. To extract useful information on these conditions from the spectra, we propose use of the color perception on the basis of the pseudo- reference white, and verify its usefulness. The result can also be used to explain the bluish color of veins in the skin tissue.
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