PROBLEM TO BE SOLVED: To provide an image having good color reproducibility by appropriately adjusting each color component when adjusting brightness. When an instruction signal that changes the brightness level of an image signal captured by a medical observation device is received, a color space that represents a signal value of the image signal and is determined by a brightness signal and a color difference signal is a hue. It is provided with a region division unit that divides the image signal into two regions, and a signal processing unit that performs different signal processing for each region of the divided color space for the image signal. [Selection diagram] Fig. 2【課題】明るさ調整を行う際に、色成分ごとに適切な調整を行うことによって色再現性がよい画像を提供する。【解決手段】医療用観察装置が撮像した画像信号の明るさレベルを変化させる指示信号を受け付けた場合、画像信号の信号値を表す色空間であって輝度信号および色差信号によって定まる色空間を色相によって２つの領域に分割する領域分割部と、画像信号に対して、分割された色空間の領域ごとに異なる信号処理を施す信号処理部と、を備える。【選択図】図２
