fixed some bug in contour detection tutorial

Author: x4nth055

machine-learning/contour-detection/contour-detector.py

@@ -12,7 +12,7 @@
 gray = cv2.cvtColor(image, cv2.COLOR_RGB2GRAY)
 
 # create a binary thresholded image
-_, binary = cv2.threshold(gray, sys.argv[2], 255, cv2.THRESH_BINARY_INV)
+_, binary = cv2.threshold(gray, int(sys.argv[2]), 255, cv2.THRESH_BINARY_INV)
 # show it
 plt.imshow(binary, cmap="gray")
 plt.show()