learnopencv/HuMoments/HuMoments.py

import cv2, sys, os
from math import copysign, log10

def main():
    showLogTransformedHuMoments = True

    for i in range(1,len(sys.argv)):

        # Obtain filename from command line argument
        filename = sys.argv[i]

        # Read image
        im = cv2.imread(filename,cv2.IMREAD_GRAYSCALE)

        # Threshold image
        _,im = cv2.threshold(im, 128, 255, cv2.THRESH_BINARY)

        # Calculate Moments
        moment = cv2.moments(im)

        # Calculate Hu Moments
        huMoments = cv2.HuMoments(moment)

        # Print Hu Moments
        print("{}: ".format(filename),end='')

        for i in range(0,7):
            if showLogTransformedHuMoments:
                # Log transform Hu Moments to make
                # squash the range
                print("{:.5f}".format(-1*copysign(1.0,\
                        huMoments[i])*log10(abs(huMoments[i]))),\
                        end=' ')
            else:
                # Hu Moments without log transform
                print("{:.5f}".format(huMoments[i]),end=' ')
        print()

if __name__ == "__main__":
    main()