PROBLEM TO BE SOLVED: To improve explanatory rate in a regression parameter and to improve measurement precision of the pigment concentration during multiple regression analysis of absorbance spectrum in skin and measurement of the pigment concentration in skin using the regression parameter.SOLUTION: By analysis of a main component for absorbance spectrum in skin, effective absorptivity spectrum εi (λ) for each of pigments is measured. A plurality of absorbance spectrums having different combination of pigment concentration Ci with a simulation model of skin are obtained. A multiple regression analysis is executed with the effective absorptivity spectrums εi (λ) for the pigments as explanatory variables. First and second regression parameters ax, ay corresponding to first and second pigments are represented by their regression parameters ai. The first and second regression parameters ax, ay are subjected to coordinate transformation so that a line connecting given points in the first pigment concentration Cx is parallel with a straight line of x=0, and a line connecting given points in the second pigment concentration Cy is parallel with a straight line of by=0. A relational expression between the first regression parameter bx subjected to the coordinate transformation and the first pigment concentration is calculated.COPYRIGHT: (C)2015,JPO&INPIT【課題】皮膚の吸光度スペクトルを重回帰分析し、その回帰パラメータを用いて皮膚中の色素濃度を測定するにあたり、回帰パラメータの説明率を改善し、色素濃度の測定精度を向上させる。【解決手段】皮膚の吸光度スペクトルの主成分分析により各色素の実効吸光係数スペクトルεi(λ)を求めておく。皮膚のシミュレーションモデルで色素の濃度Ciの組み合わせを異ならせた複数の吸光度スペクトルを求め、それを前記色素の実効吸光係数スペクトルεi(λ)を説明変数として重回帰分析し、その回帰パラメータaiで第1、第2の色素に対応する第1、第2の回帰パラメータax、ayを表す。第1、第2の回帰パラメータax、ayを座標変換し、第1の色素濃度Cxが一定の点を結んだ線とbx=0の直線とが平行となり、第2の色素濃度Cyが一定の点を結んだ線とby=0の直線とが平行となるようにする。座標変換後の第1の回帰パラメータbxと第1の色素濃度との関係式を求める。【選択図】図1A
