java - cvHaarDetectObjects() 方法有什么作用？

Question

请专家解释一下，是否可以使用cvHaarDetectObjects()方法来检测正方形并获取宽度和高度？我找到了一个使用这种方法进行人脸检测的代码，但我需要知道我是否可以将它用于矩形检测。

    String src="src/squiredetection/MY.JPG";
    IplImage grabbedImage = cvLoadImage(src);
    IplImage grayImage    = IplImage.create(grabbedImage.width(),  grabbedImage.height(), IPL_DEPTH_8U, 1);

        cvCvtColor(grabbedImage, grayImage, CV_BGR2GRAY);

        CvSeq faces = cvHaarDetectObjects(grayImage, cascade, storage, 1.1, 3, 0);//*
        for (int i = 0; i < faces.total(); i++) {
            CvRect r = new CvRect(cvGetSeqElem(faces, i));
            cvRectangle(grabbedImage, cvPoint(r.x(), r.y()), cvPoint(r.x()+r.width(), r.y()+r.height()), CvScalar.RED, 1, CV_AA, 0);
         /*   hatPoints[0].x = r.x-r.width/10;    hatPoints[0].y = r.y-r.height/10;
            hatPoints[1].x = r.x+r.width*11/10; hatPoints[1].y = r.y-r.height/10;
            hatPoints[2].x = r.x+r.width/2;     hatPoints[2].y = r.y-r.height/2;*/
          //  cvFillConvexPoly(grabbedImage, hatPoints, hatPoints.length, CvScalar.GREEN, CV_AA, 0);
        }

当我使用上面的方法时，它抛出以下异常

OpenCV Error: Bad argument (Invalid classifier cascade) in unknown function, file C:\slave\WinInstallerMegaPack\src\opencv\modules\objdetect\src\haar.cpp, line 1036
Exception in thread "main" java.lang.RuntimeException: C:\slave\WinInstallerMegaPack\src\opencv\modules\objdetect\src\haar.cpp:1036: error: (-5) Invalid classifier cascade

    at com.googlecode.javacv.cpp.opencv_objdetect.cvHaarDetectObjects(Native Method)
    at com.googlecode.javacv.cpp.opencv_objdetect.cvHaarDetectObjects(opencv_objdetect.java:243)
    at squiredetection.Test2.main(Test2.java:52 I have put * on this line)

请提供简单的代码示例。

Answer 1

cvHaarDetectObjects() 不仅用于面部检测对象或形状，它依赖于 HaarCascade 分类器。

如果你传递face haarcascade xml，那么它会返回一个面孔数组，或者也可以使用eye、nose等HaarCascade XML文件.您还可以通过使用 opencv_traincascade.exe

创建自己的正样本和负样本来制作自定义 haarcascade xml

CvSeq faces = cvHaarDetectObjects(grayImage, classifier, storage,
                1.1, 3, CV_HAAR_DO_CANNY_PRUNING);

for (int i = 0; i < faces.total(); i++) {
   // its ok
}

关于 opencv doc 的详细信息

矩形检测:

there is an example for rectangle detection in OpenCV, they use it to detect the squares in a chessboard. Have a look to squares.c in ..\OpenCV\samples\c\ directory.

看这个chessboard detection sample in opencv

Invalid classifier cascade in unknown function 错误表示您传递的分类器格式不正确或缺少某些内容。检查您的分类器 xml 文件是否有效。