1. An apparatus for generating an image description vector comprising: an encoding unit configured for encoding each of a plurality of pixel regions of an image into M pieces of N-bit binary codes, wherein each bit of an N-bit binary code represents a neighbouring pixel region which is in a neighbourhood of a corresponding pixel region; and a generating unit configured for generating an image description vector of the image based on matching at least one of the M pieces of N-bit binary code of each pixel region of the plurality of pixel regions with a particular code pattern, where M is an integer of 3 or larger, and N is an integer of 3 or larger.