Question

For the image given below (provided with the assignment handout), apply the connectected component labelling and count the total number of white objects. First threshold the images and then do connected component analysis. (40 Marks)

how can we count the total number of white objects in the image using open CV function of python for pixel processing? The image is also attached kindly help.

The course is digital image processing

Answer 1

# Standard imports
import cv2
import numpy as np;

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

#Apply treshold
ret,im = cv2.threshold(im,240,255,cv2.THRESH_BINARY)

kernel = np.ones((6,6),np.uint8)
erosion = cv2.erode(im,kernel,iterations = 1)
opening = cv2.morphologyEx(im, cv2.MORPH_OPEN, kernel)
im = cv2.morphologyEx(opening, cv2.MORPH_CLOSE, kernel)

# Setup SimpleBlobDetector parameters.
params = cv2.SimpleBlobDetector_Params()

#filter by color
params.filterByColor = True
params.blobColor = 255

# Filter by Convexity
params.filterByConvexity = True
params.minConvexity = 0.87

# Filter by Inertia
params.filterByInertia = True
params.minInertiaRatio = 0.08

# Create a detector with the parameters
ver = (cv2.__version__).split('.')
if int(ver[0]) < 3 :
detector = cv2.SimpleBlobDetector(params)
else :
detector = cv2.SimpleBlobDetector_create(params)

# Detect blobs.
keypoints = detector.detect(im)

# Draw detected blobs as red circles.
# cv2.DRAW_MATCHES_FLAGS_DRAW_RICH_KEYPOINTS ensures the size of the circle corresponds to the size of blob
im_with_keypoints = cv2.drawKeypoints(im, keypoints, np.array([]), (0,0,255), cv2.DRAW_MATCHES_FLAGS_DRAW_RICH_KEYPOINTS)

# Show keypoints
cv2.imwrite("C:/opencvTests/keypoints.jpg",im_with_keypoints)
print("Total of objects")
print(len(keypoints))

This code will do your job.