1. A feature extracting apparatus comprising: a receiver that receives a window region image which is a partial region of a target image taken through a lens; and a control circuitry, wherein the control circuitry is operative to: set, for each of a plurality of pixels included in the window region image, a pixel as a pixel of interest and acquire pixel values of a plurality of comparison target pixels included in an annular neighborhood region having the pixel of interest at its center; calculate a difference between the pixel value of the pixel of interest and the pixel value of each of the comparison target pixels; and generate, for each of the plurality of pixels, a local binary pattern indicating, using bit values, whether the difference between the pixel value of the pixel and the pixel value of each of the comparison target pixels is equal to or greater than a predetermined threshold, wherein a plurality of the neighborhood regions are present for each of the pixels of interest, and a distance between the plurality of neighborhood regions is determined based on spatial frequency characteristics of the lens.