1. A feature amount calculation apparatus that calculates a feature amount of a target object from image data, the feature amount calculation apparatus comprising: a feature value calculator that calculates an edge direction and an edge magnitude as input image data pixel-unit feature values; an edge direction group calculator that combines the edge directions of a plurality of pixels and calculates an edge direction group as an inter-pixel feature amount; a correlation value calculator that takes all pixels or predetermined pixels of the plurality of pixels used in the feature value calculation as pixels subject to correlation value calculation, and calculates a correlation value of the edge magnitudes between the pixels subject to correlation value calculation for each feature amount; and a histogram creator that counts the feature amounts in a histogram for each correlation value, and creates the histogram as a feature vector, wherein: the edge direction group calculator calculates a group of edge direction values of a plurality of pixels in a predetermined space-time arrangement relationship as the feature amount; and the correlation value calculator takes the plurality of pixels used in calculation of the feature amount as the pixels subject to correlation value calculation.