An image of a test chart having a test pattern is taken with an electronic endoscope. A DSP of a processing device generates a test pattern image from image signals input from the electronic endoscope. An image compositor composites the test pattern image and a test mask image having a predetermined reference pattern and generates a test mask composite image. An inspector visually measures positional and rotational displacement amounts of the test pattern with respect to the reference pattern in the test mask composite image displayed on a monitor, and inputs measurement results as displacement amount information to the processing device. The displacement amount information is stored in an EEPROM of the electronic endoscope. The processing device calibrates an endoscope image of a body cavity based on the displacement amount information input from the electronic endoscope.
