什么是opencv中的V4L/AVLD ?

我遵循本页的说明:http://wiki.elphel.com/index.php?title=OpenCV_Tennis_balls_recognizing_tutorial探测网球。这段代码可以在Python上运行，它的要求是形态学操作的V4L/AVLD。使用功能cvClose()和cvOpen()对掩膜进行扩张和侵蚀。我用c++写代码，所以用cvDilate()和cvErode()代替，但结果不如那个网站好。

这是我的结果:output.jpg。(很抱歉，因为我没有足够的声誉来发布图片T_T)以下是我的完整代码:

#include "highgui.h"
#include "cv.h"
void main()
{
    IplImage* img = cvLoadImage("tennis.jpg",1);
    CvSize size = cvGetSize(img);
    IplImage *hsv = cvCreateImage(size, IPL_DEPTH_8U, 3);
    cvCvtColor(img, hsv, CV_BGR2HSV);
    CvMat *mask = cvCreateMat(size.height, size.width, CV_8UC1);
    cvInRangeS(hsv, cvScalar(0.11*256, 0.60*256, 0.20*256, 0),
                    cvScalar(0.14*256, 1.00*256, 1.00*256, 0), mask);
    cvReleaseImage(&hsv);
    IplConvKernel *se21 = cvCreateStructuringElementEx(21, 21, 10, 10, CV_SHAPE_RECT, NULL);
    IplConvKernel *se11 = cvCreateStructuringElementEx(11, 11, 5,  5,  CV_SHAPE_RECT, NULL);
    cvErode(mask, mask, se21); 
    cvDilate(mask, mask, se11);   
    cvReleaseStructuringElement(&se21);
    cvReleaseStructuringElement(&se11);
    /* Copy mask into a grayscale image */
    IplImage *hough_in = cvCreateImage(size, 8, 1);
    cvCopy(mask, hough_in, NULL);
    cvSmooth(hough_in, hough_in, CV_GAUSSIAN, 15, 15, 0, 0);
    /* Run the Hough function */
    CvMemStorage *storage = cvCreateMemStorage(0);
    CvSeq *circles = cvHoughCircles(hough_in, storage,CV_HOUGH_GRADIENT, 4, size.height/10, 100, 40, 0, 0);
    cvReleaseMemStorage(&storage);
    int i;
    for (i = 0; i < circles->total; i++) {
         float *p = (float*)cvGetSeqElem(circles, i);
         CvPoint center = cvPoint(cvRound(p[0]),cvRound(p[1]));
         CvScalar val = cvGet2D(mask, center.y, center.x);
         if (val.val[0] < 1) continue;
             cvCircle(img,  center, 3,             CV_RGB(0,255,0), -1, CV_AA, 0);
             cvCircle(img,  center, cvRound(p[2]), CV_RGB(255,0,0),  3, CV_AA, 0);
             cvCircle(mask, center, 3,             CV_RGB(0,255,0), -1, CV_AA, 0);
             cvCircle(mask, center, cvRound(p[2]), CV_RGB(255,0,0),  3, CV_AA, 0);
    }
    cvNamedWindow( "Output", CV_WINDOW_AUTOSIZE );
    cvShowImage( "Output", img );
    cvNamedWindow( "mask", CV_WINDOW_AUTOSIZE );
    cvShowImage( "mask", mask );
    cvWaitKey(0);
}

有人能帮我得到V4L/AVLD和改进这个代码吗?非常感谢。