<title>Natural color reproduction of human skin for telemedicine</title>

Abstract

For a reliable diagnosis through visual telecommunication systems, it is very important to reproduce patient images with correct color. Natural color television system previously proposed is capable of reproducing the original color of the objects using multispectral images, even when the illumination environment for observing images is different from the illumination used for recording. In this paper, to render this system practical for telemedicine system, we reduce the number of color bands of multispectral camera by utilizing the principal components of spectral reflectances in human skin class. In addition, we investigate a simple method, using color charts, to obtain the recording information of both illumination and camera. As a color chart selection criterion, it becomes clear that principal components for human skin class need to be described by the linear combination of spectral reflectances of color charts. Principal components for human skin class are obtained through measurements and analysis of 484 human skin spectral reflectances. In the experiment, natural color reproduction for human skin is realized from limited number of color bands using color charts for acquiring the recording information instead of spectral measurement devices.

<title>High-fidelity image reproduction using angular distribution of reflected spectral intensity</title>

“…(4) As C(Ø) represents the similarity between I, (2,0) and En(2) , and if C(Ø) takes minimum at çb = çb 1(2, Ø) does not contain specular reflection.On the other hand, integration of eq. Based on this idea and the assumption that there is at least an image that does not contains specular component for a point on the surface, we define C(Ø) as C(Ø) = Ji, (2, O)E (2)d2 .…”

Natural color reproduction system for telemedicine

“…Ref. [2] describes about these measurements and analysis in detail and examinations on the number of color bands required for accurate color estimation from the cumulative proportion rates of the principal components. From this investigation we can conclude that 5-band images are almost sufficient for color reproduction of human skin.…”

“…In ref. [2], this method was first proposed and described in detail. Besides, this method can also acquire the camera spectral sensitivities at a time.…”

“…Then, to obtain spectral reflectances of the object f(λ), the multispectral image of the object is captured by a multispectral camera. The spectral reflectance function f(λ) is estimated by using the principal components [2][3][4][5] of the spectral reflectance of the object class, such as human skin. If the spectral reflectance of the object class can be described by R principal components e i (λ)(i=1,…,R) with good accuracy, then the reflectance f(λ) can be approximately expressed as,…”

“…We have developed a method for natural color reproduction [1,2], which uses a multispectral image to obtain spectral information of the object, and color signal processing for illumination correction and monitor calibration is performed. In this paper, we introduce the prototype system developed for the reproduction of patient image, as well as the experimental results using a multispectral camera to demonstrate the capability of the developed system.…”