PROBLEM TO BE SOLVED: To accurately calculate the degree of oxygen saturation of blood hemoglobin even if an image contains an area of which brightness is different.SOLUTION: The inside of a subject is irradiated alternately with first white light containing first blue laser light and first fluorescence, and second white light containing second blue laser light and second fluorescence. B1 image signal, G2 image signal, R1 image signal, and R2 image signal among the image signals obtained by imaging the subject by a sensor are used to calculate the degree of oxygen saturation. The B1 image signal and G2 image signal are used to calculate the amount of deviation of the subject. Registration between the R1 image signal and the R2 image signal is performed on the basis of the amount of deviation of the subject. A reference signal ratio (R2/R1) is determined from the R1 image signal and R2 image signal for which the registration was performed. The G2 image signal or R2 image signal is corrected on the basis of the reference signal ratio. The degree of oxygen saturation is calculated on the basis of the B1 image signal and the G2 image signal or R2 image signal after correction.COPYRIGHT: (C)2015,JPO&INPIT【課題】画像中に明るさが異なる領域が存在しても、血中ヘモグロビンの酸素飽和度を精度良く算出する。【解決手段】第1青色レーザ光と第1蛍光を含む第1白色光と、第2青色レーザ光と第2蛍光を含む第2白色光は、交互に検体内に照射される。検体をセンサで撮像して得られる画像信号のうち、B1画像信号、G2画像信号、R1画像信号、R2画像信号を酸素飽和度の算出に使用する。B1画像信号とG2画像信号から、検体の位置ずれ量を算出する。この検体の位置ずれ量に基づいて、R1画像信号及びR2画像信号間の位置合わせを行う。位置合わせ済みのR1画像信号及びR2画像信号から、参照用信号比(R2/R1)を求める。この参照用信号比に基づいて、G2画像信号又はR2画像信号を補正する。B1画像信号と補正後のG2画像信号又はR2画像信号に基づいて、酸素飽和度を算出する。【選択図】図9
