#include<cv.h>
#include<highgui.h>
int main(int argc, char** argv){
CvMat* mat = cvCreateMat(100,100, CV_8SC3);
cvZero(mat);
cvCircle(mat, cvPoint(50, 50), 30, cvScalar(0xff, 0xff, 0xff));
cvNamedWindow("cvCircle",CV_WINDOW_AUTOSIZE);
cvShowImage("cvCircle", mat);
cvWaitKey(0);
}