The power spectrum operation means which calculate the two-dimensional power spectrum of that image

摘要

The two-dimensional power spectrum of an input image, which is obtained by computing its two-dimensional Fourier transform, is segmented into a plurality of blocks (5x5) on the two-dimensional coordinate system, and the standard deviations of power spectrum components of blocks (5x3) of interest of those segmented blocks are computed. By masking the computed standard deviations in units of blocks (matrix of standard deviations) using predetermined mask patterns prepared in units of directions of interest, the sums of the standard deviations are computed as feature amounts in units of directions, and the directionality of the input image is determined based on the feature amounts. The feature amounts computed for the input image and the directionality determination result are stored in correspondence with each other, and a similar image search is made using the stored information.