04_FAST.py

import numpy as np
import cv2
from matplotlib import pyplot as plt

img = cv2.imread('b.jpg')
img = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

# Initiate FAST object with default values
fast = cv2.FastFeatureDetector_create(40)

# find and draw the keypoints
kp = fast.detect(img,None)
img2 = cv2.drawKeypoints(img, kp, color=(255,0,0), outImage = None)
cv2.imshow('Fast true', img2)
cv2.waitKey(0)
cv2.destroyAllWindows()
cv2.imwrite('fast_true.png',img2)


# Print all default params
print("Threshold: ", fast.getThreshold)
print("nonmaxSuppression: ", fast.getNonmaxSuppression())
print("neighborhood: ", fast.getType())
print("Total Keypoints with nonmaxSuppression: ", len(kp))
# Nonmax Suppression : It detects the object only once with the highest probability and removes the other ones.


cv2.imshow('Fast true', img2)
cv2.waitKey(0)
cv2.destroyAllWindows()

# Disable nonmaxSuppression
fast.setNonmaxSuppression(False)
kp = fast.detect(img,None)

print("Total Keypoints without nonmaxSuppression: ", len(kp))

img3 = cv2.drawKeypoints(img, kp, color=(255,0,0), outImage = None)

cv2.imshow('fast_false', img3)
cv2.waitKey(0)
cv2.destroyAllWindows()