An image matching apparatus matching a first image against a second image, the image matching apparatus comprising: an acquiring unit configured to acquire a frequency feature of the first image and a frequency feature of the second image; a generating unit configured to synthesize the frequency feature of the first image and the frequency feature of the second image, and generate a quantized synthesized frequency feature in which each element is represented by a binary value or a ternary value; and a determining unit configured to calculate a score indicating a degree to which the quantized synthesized frequency feature is a square wave having a single period, and match the first image against the second image based on the score, wherein the generating unit includes: a synthesizing unit configured to synthesize the frequency feature of the first image and the frequency feature of the second image, and generate a synthesized frequency feature, the synthesized frequency feature being a cross power spectrum; and a quantizing unit configured to transform each element, which is a complex number composed of a real part and an imaginary part, of the synthesized frequency feature generated by the synthesizing unit into a binary value or a ternary value, and wherein the quantizing unit is configured to transform each element into a binary value or a ternary value based on a sign of a predetermined one of the real part and the imaginary part of the element. an acquiring unit configured to acquire a frequency feature of the first image and a frequency feature of the second image; a generating unit configured to synthesize the frequency feature of the first image and the frequency feature of the second image, and generate a quantized synthesized frequency feature in which each element is represented by a binary value or a ternary value; and a determining unit configured to calculate a score indicating a degree to which the quantized synthesized frequency feature is a square wave having a single period, and match the first image against the second image based on the score, wherein the generating unit includes: a synthesizing unit configured to synthesize the frequency feature of the first image and the frequency feature of the second image, and generate a synthesized frequency feature, the synthesized frequency feature being a cross power spectrum; and a quantizing unit configured to transform each element, which is a complex number composed of a real part and an imaginary part, of the synthesized frequency feature generated by the synthesizing unit into a binary value or a ternary value, and wherein the quantizing unit is configured to transform each element into a binary value or a ternary value based on a sign of a predetermined one of the real part and the imaginary part of the element. a synthesizing unit configured to synthesize the frequency feature of the first image and the frequency feature of the second image, and generate a synthesized frequency feature, the synthesized frequency feature being a cross power spectrum; and a quantizing unit configured to transform each element, which is a complex number composed of a real part and an imaginary part, of the synthesized frequency feature generated by the synthesizing unit into a binary value or a ternary value, and wherein the quantizing unit is configured to transform each element into a binary value or a ternary value based on a sign of a predetermined one of the real part and the imaginary part of the element.