contour-detector.py

import cv2
import matplotlib.pyplot as plt
import sys

# read the image
image = cv2.imread(sys.argv[1])

# convert to RGB
image = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)

# convert to grayscale
gray = cv2.cvtColor(image, cv2.COLOR_RGB2GRAY)

# create a binary thresholded image
_, binary = cv2.threshold(gray, int(sys.argv[2]), 255, cv2.THRESH_BINARY_INV)
# show it
plt.imshow(binary, cmap="gray")
plt.show()

# find the contours from the thresholded image
contours, hierarchy = cv2.findContours(binary, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)

# draw all contours
image = cv2.drawContours(image, contours, -1, (0, 255, 0), 2)

# show the image with the drawn contours
plt.imshow(image)
plt.show()