HOG描述符出错

Question

我正在使用HOG描述符进行特征提取。我正在使用visual studio 2012和opencv 2.4.9版本。我在hog.compute函数中遇到运行时错误。

int main()
{
     Mat img_raw = imread("p1.jpg", 1); // load as color image.    
     Mat img;
     cvtColor(img_raw, img, CV_RGB2GRAY);

     HOGDescriptor hog;
     vector<float> descriptor;
     vector<Point>locations;

     hog.compute(img, descriptor,Size(32,32),Size(0,0),locations);   

     cout << "HOG descriptor size is " << hog.getDescriptorSize() << endl;
     cout << "img dimensions: " << img.cols << " width x " << img.rows <<     "height" << endl;
     cout << "Found " << descriptor.size() << " descriptor values" << endl;
     cout << "Nr of locations specified : " << locations.size() << endl;
     return 0;

}