1. An image feature generating device comprising: an image feature generation unit configured so as to generate image feature data of input image data for similarity calculation between the input image data and other image data; and a transformation unit configured so as to transform the input image data to produce two or more coefficients in a frequency domain, wherein the image feature generating device is configured so as to generate the image feature data by quantizing the two or more coefficients in a manner that, for each component of the two or more coefficients, finer quantization is carried out on a range of a portion having a smaller amplitude and coarser quantization is carried out on a range of a portion having a larger amplitude, and wherein the two or more coefficients comprise coefficients other than two or more DC components.