Method for extracting features of a thermal image

A method for extracting features of a thermal image, comprising:

• reading the thermal image, and dividing the thermal image into a plurality of block images;
• and
• extracting a histogram of oriented gradient (HOG) feature histogram from each of the plurality of block images, and transforming the HOG feature histogram of each of the plurality of block images into a symmetric weighting HOG (SW-HOG) feature histogram;
• wherein the SW-HOG feature histogram is obtained by multiplying a histogram of gradient intensity distribution by a block weighting, and the block weighting is:
• w
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• wherein Bi represents a block image within the plurality of block images, w(Bi) represents the block weighting of the block image Bi, d(Bi) represents gradient intensity of the block image Bi, and {cil,t(j), cil,b(j), cir,t(j), cir,b(j)} represent intensity of a top-left corner cell image, a bottom-left corner cell image, a top-right corner cell image and a bottom-right corner cell image, respectively.