Image identity scale calculation stystem

An image identity scale calculation method for calculating an identity scale representing a degree of identity of two images, the method comprising:

• being supplied as inputs with hierarchical quantization index codes, which are encodings allowing unique specification of quantization indexes of a plurality of hierarchies calculated by hierarchical quantization for each quantization target region of the two images in accordance with a previously defined hierarchical quantization method, selecting a quantization index set used for comparison as a comparing quantization index set based on additionally supplied information, comparing the hierarchical quantization index codes of the two images by using the comparing quantization index set, thereby calculating an identity scale of the two images, by an image feature comparison unit.

A non-transitory computer-readable medium storing a computer program comprising instructions for causing a computer calculating an identity scale representing a degree of identity of two images to function as an image feature comparison unit configured to:

• be supplied as inputs with hierarchical quantization index codes, which are encodings allowing unique specification of quantization indexes of a plurality of hierarchies calculated by hierarchical quantization for each quantization target region of the two images in accordance with a previously defined hierarchical quantization method, select a quantization index set used for comparison as a comparing quantization index set based on additionally supplied information, and compare the hierarchical quantization index codes of the two images by using the comparing quantization index set, thereby calculating the identity scale of the two images.