Operation program, operation method, and operation device

An operation method comprising:

• a feature quantity acquiring process of acquiring a feature quantity which is extracted from an input image;
• a reconstruction error calculating process of calculating a reconstruction error on the basis of a difference between the acquired feature quantity and an average which is determined in advance on the basis of a normal image;
• and
• an output process of outputting a result of calculation in the reconstruction error calculating process.

An operation device comprising:

• a feature quantity acquiring unit configured to acquire a feature quantity which is extracted from an input image;
• a reconstruction error calculating unit configured to calculate a reconstruction error on the basis of a difference between the acquired feature quantity and an average which is determined in advance on the basis of a normal image;
• and
• an output unit configured to output a result of calculation from the reconstruction error calculating unit.