A feature extracting apparatus includes a pixel feature calculator that
calculates a pixel feature for each pixel of image data; an area setting
unit configured to set a plurality of areas in the image data; a
coordinate mapping unit configured to map a first coordinate in one of
the plurality of areas onto a second coordinate in at least one of the
other plurality of areas; and a co-occurrence matrix calculator
configured to calculate a co-occurrence matrix for each of the plurality
of areas, the co-occurrence matrix being frequency of combinations of the
pixel features at the first coordinate and the pixel feature at the
second coordinates.