1. A system for efficient image feature extraction, comprising a buffer for storing a slice of at least a first plurality n of lines of gradient direction pixel values of a directional gradient image, said buffer having a buffer input for receiving said first plurality n of lines and a buffer output for providing a second plurality m of columns of gradient direction pixel values of said slice to a score network input of a score network, said score network comprising: a plurality of comparators for comparing said gradient direction pixel values of said second plurality of columns with corresponding reference gradient direction pixel values of a reference directional gradient pattern of a shape; and a plurality of adders for providing partial score values depending on output values of said comparators to one or more score network outputs, said one or more score network outputs coupled to one or more corresponding accumulation network inputs of an accumulation network having an accumulation network output for providing a final score value depending on said partial score values.