PROBLEM TO BE SOLVED: To provide an endoscope having a need for switching operation modes between observation under normal light and observation under a special light, which appropriately switches the operation modes by itself without control from outside.SOLUTION: An endoscope includes an illumination part capable of irradiating a plurality types of illumination lights, an imaging part for generating an image signal for a subject, a color extraction part for extracting a color component of the image signal in a screen of one frame in the image signal, a color index value variation calculation part for calculating a predetermined color index value for each frame based on an average of the color component, and calculating an inter-frame variation of the color index value, a light source determination part for determining a type of the illumination light based on an increased/decreased value in the inter-frame variation of the color index value and the color index value related to a preceding frame, and an imaging mode switching part for switching imaging modes of the endoscope corresponding to the determined type of the illumination light.SELECTED DRAWING: Figure 2COPYRIGHT: (C)2017,JPO&INPIT【課題】通常光観察時と特殊光観察時とで動作モードの切り換えを要する内視鏡において、外部からの制御に拠らず自ら適切に動作モードを切り換える。【解決手段】複数種類の照明光を照射可能な照明部と、被写体の画像信号を生成する撮像部と、画像信号の1フレームの画面における当該画像信号の色成分を抽出する色抽出部と、前記色成分の平均値に基づく各フレーム毎の所定色指標値を計算すると共に、当該色指標値のフレーム間変化値を計算する色指標値変化量計算部と、前記色指標値のフレーム間変化値の増減値と、前のフレームに係る色指標値と、に基づいて照明光の種類を判別する光源判別部と、判定された照明光の種類に対応する当該内視鏡の撮像モードを切り換える撮影モード切換部と、を備える。【選択図】図2
