An observation system includes a light source device capable of generating light of a plurality of different wavelength bands as illumination light for illuminating a living tissue, and a light source device of generating light of a plurality of wavelength bands at a predetermined light amount ratio A light source control unit that controls the light source and one or more structures included in the biological tissue based on a desired degree of enhancement with respect to an image obtained by imaging the return light from the biological tissue illuminated by the illumination light A light quantity ratio for controlling a light quantity ratio of light in at least two wavelength bands out of light in a plurality of wavelength bands based on a setting of a desired enhancement degree and a predetermined emphasis process for displaying. A control unit configured to output a control signal to the light source control unit and to perform control for causing the enhancement processing unit to perform a predetermined enhancement process. 観察システムは、生体組織を照明するための照明光として、相互に異なる複数の波長帯域の光を発生可能な光源装置と、複数の波長帯域の光を所定の光量比で発生するように光源装置を制御する光源制御部と、照明光により照明された生体組織からの戻り光を撮像して得られた画像に対し、所望の強調度合いに基づき生体組織に含まれる１つ以上の構造物を強調表示させるための所定の強調処理を施す強調処理部と、所望の強調度合いの設定に基づき、複数の波長帯域の光のうちの少なくとも２つの波長帯域の光の光量比を制御するための光量比制御信号を光源制御部に出力するとともに、所定の強調処理を行わせるための制御を強調処理部に対して行うように構成された制御部と、を有する。
