IMAGE SORTING METHOD

An image sorting method includes: inputting a two-dimensional distribution function of a color plane image; sequentially generating a high-frequency subband image from plural resolutions by filtering the color plane image, generating a high-frequency image by sequentially combining the high-frequency subband images from low resolution, preparing a two-dimensional distribution function of an edge plane image that's defined by raising each pixel value of the high-frequency image to a second power; expanding the two-dimensional distribution functions of the color plane image and edge plane image into a two-dimensional Legendre series and two-dimensional Fourier series, respectively, describing the two-dimensional color distributions of the color plane image and edge plane image by a Legendre expansion coefficient and a Fourier expansion coefficient, respectively; evaluating the distribution of the color plane image based on the Legendre and Fourier expansion coefficients; and sorting the color plane image into images of multiple categories based on the evaluation.