System and method for comparing dental X-ray images

A system for comparing dental X-ray images comprising:

• a positional displacement calculator configured to calculate a positional displacement between a dental X-ray test image and a dental X-ray reference image, by using phase-only correlation;
• a positional displacement corrector configured to correct the positional displacement;
• a base point extractor configured to define, as a base image, any one of the dental X-ray test image and the dental X-ray reference image between which the positional displacement is corrected, to define, as a corresponding image, the other one of the two dental images, and to extract a plurality of base points from the base image;
• a corresponding point extractor configured to extract a plurality of corresponding points, which correspond to the plurality of base points, from the corresponding image;
• a correspondence calculator configured to calculate correspondence between the plurality of base points and the plurality of corresponding points nonlinearly distorted from the plurality of base points;
• a nonlinear distortion corrector configured to correct a nonlinear distortion between the base image and the corresponding image, based on the correspondence;
• and
• a similarity calculator configured to find, by using phase-only correlation, a similarity between the base image and the corresponding image between which the nonlinear distortion is corrected.