Abstract: A local feature amount calculating device includes a local feature amount calculating unit that acquires a local feature amount of a feature point for each pixel by giving a vote of a strength of the direction of a pixel, which is calculated by a direction strength calculating unit, to a vote cell to which a pixel of interest belongs out of vote cells of a rotated vote cell pattern that is acquired by rotating a reference vote cell pattern by an angle corresponding to a main axis direction along a corrected edge gradient direction that is acquired by correcting an edge gradient direction of the pixel that is calculated by a direction strength calculating unit in accordance with the main axis direction.

Abstract: A local feature amount calculating device includes a local feature amount calculating unit that acquires a local feature amount of a feature point for each pixel by giving a vote of a strength of the direction of a pixel, which is calculated by a direction strength calculating unit, to a vote cell to which a pixel of interest belongs out of vote cells of a rotated vote cell pattern that is acquired by rotating a reference vote cell pattern by an angle corresponding to a main axis direction along a corrected edge gradient direction that is acquired by correcting an edge gradient direction of the pixel that is calculated by a direction strength calculating unit in accordance with the main axis direction.

Abstract: A bit code converter transforms a learning feature vector using a transformation matrix updated by a transformation matrix update unit, and converts the transformed learning feature vector into a bit code. When the transformation matrix update unit substitutes a substitution candidate for an element of the transformation matrix, a cost function calculator fixes the substitution candidate that minimizes a cost function as the element. The transformation matrix update unit selects the element while sequentially changing the elements, and the cost function calculator fixes the selected element every time the transformation matrix update unit selects the element, thereby finally fixing the optimum transformation matrix.