Mat img0 = imread(filename, 1); // img0----CV_8UC3
cvtColor(img0, gray, COLOR_BGR2GRAY); // gray----CV_8UC1
gray = Scalar::all(0);
/*检测轮廓*/
findContours(gray, contours, hierarchy, CV_RETR_CCOMP, CV_CHAIN_APPROX_SIMPLE);
将上面第二行和第三行改成 :Mat gray(img0.size(),CV_8UC1,Scalar::all(0));
再用下面的检测轮廓函数检测出的contours一直为0 怎么回事?请大神们指教!