OpenCv在Python上挣扎

Question

import cv2  
import sys

# Get user supplied values
imagePath = sys.argv[1]
cascPath = sys.argv[2]

# Create the haar cascade
faceCascade = cv2.CascadeClassifier(cascPath)

# Read the image
image = cv2.imread(imagePath)
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)

# Detect faces in the image
faces = faceCascade.detectMultiScale(
    gray,
    scaleFactor=1.1,
    minNeighbors=5,
    minSize=(30, 30)
    #flags = cv2.CV_HAAR_SCALE_IMAGE
)

print("Found {0} faces!".format(len(faces)))

# Draw a rectangle around the faces
for (x, y, w, h) in faces:
    cv2.rectangle(image, (x, y), (x+w, y+h), (0, 255, 0), 2)

cv2.imshow("Faces found", image)
cv2.waitKey(0)  

我安装了OpenCv并找到了一个示例代码。但令人惊讶的是它没有用。我运行它时收到此错误消息。

Traceback (most recent call last):
  File "/Users/Esat/Desktop/Python/Softwares/untitled.py", line 5, in <module>
    imagePath = sys.argv[1]
IndexError: list index out of range

我该怎么办？