PROBLEM TO BE SOLVED: To simultaneously display both a normal image and a spectral image with proper brightness.SOLUTION: A rotary filter provided alternately with dimmer filters having a predetermined dimming factor and band limiting filters along a circumferential direction is rotated on an optical path in a simultaneous display mode for simultaneously displaying a normal observation image and a spectral image on a monitor, and narrow-band light and white light are alternately irradiated to an observation part. Gain processing is applied to an image signal corresponding to the narrow-band light read from an image sensor to increase the brightness of the spectral image. The dimming factor is determined in accordance with a gain value so as to equalize the brightness of the normal image and the spectral image.COPYRIGHT: (C)2014,JPO&INPIT【課題】通常画像と分光画像両方を適切な明るさで同時表示させる。【解決手段】通常観察画像と分光画像をモニタに同時表示する同時表示モードにおいて、所定の減光率を有する減光フィルタと帯域制限フィルタを交互に周方向に沿って設けた回転フィルタを光路上において回転させ、狭帯域光と白色光を交互に観察部位へ照射させる。イメージセンサから読み出される狭帯域光に応じた画像信号に対してゲイン処理を施し、分光画像の明るさを増加させる。減光率は、通常画像と分光画像の明るさが等しくなるように、ゲイン値に応じて定められる。【選択図】図7
