Image analysis apparatus for calculating degree of change in distribution characteristic values, image analysis system, and method for operating image analysis system

An image analysis apparatus includes a region extraction unit configured to determine, as analysis target regions, respective predetermined regions in a first image and a second image that are acquired at timings before and after execution of a predetermined action to a subject and inputted through an image input unit in a state where an endoscope is continuously inserted in the subject, a distribution characteristic value calculation unit configured to obtain a first distribution characteristic value by extracting a color component of the analysis target region in the first image, and to obtain a second distribution characteristic value by extracting a color component of the analysis target region in the second image, and an image analysis unit configured to calculate the degree of change in the second distribution characteristic value with respect to the first distribution characteristic value.