SurfFeatureDetector探测器（400）; SyntaxError：语法无效

Question

我正在尝试使用opencv中的SurfFeatureDetector来检测关键点，不幸的是它不能正常工作。任何人都知道为什么？

这是我的代码的和平：

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

img1 = imread("C:/Work/Python/in/150903_090428_Image007.jpg", CV_LOAD_IMAGE_GRAYSCALE);
img2 = imread("C:/Work/Python/in/150903_094605_Image003.jpg", CV_LOAD_IMAGE_GRAYSCALE);

#detecting keypoints
SurfFeatureDetector detector(400);
vector<KeyPoint> keypoints1, keypoints2;
detector.detect(img1, keypoints1);
detector.detect(img2, keypoints2);

这是我的错误：

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Users\Magda\Anaconda\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py", line 685, in runfile
    execfile(filename, namespace)
  File "C:\Users\Magda\Anaconda\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py", line 71, in execfile
    exec(compile(scripttext, filename, 'exec'), glob, loc)
  File "C:/Work/Python/in/Images_manipulation_v3.py", line 9
    SurfFeatureDetector detector(400);
                               ^
SyntaxError: invalid syntax
>>> 

我正在使用OpenCV 2.4.9，Visual Studio 2013，| Anaconda 2.3.0（64位）和Python 2.7.10，Windows 10。