opencv_显示鼠标点击处像素的颜色值

#include <cv.h>
#include <highgui.h>
void myMouseCallback(int event,int x,int y,int flags,void* param)
{
IplImage* img = (IplImage*)param;
IplImage* img1 = cvCloneImage(img);
CvFont font;
char text[20];
uchar* ptr;
cvInitFont(&font, CV_FONT_HERSHEY_PLAIN, .8, .8, 0, 1, 8);

if(event == CV_EVENT_LBUTTONDOWN)
{
ptr = cvPtr2D(img1, y, x, NULL);
sprintf(text,"(%d,%d,%d)",ptr[2],ptr[1],ptr[0]);

cvPutText(img1,text,cvPoint(x,y),&font,CV_RGB(255,0,255));
cvShowImage("MyWindow",img1);
}
}
int main( int argc, char* argv[] )
{
IplImage* img = cvLoadImage("1.jpg");
cvNamedWindow("MyWindow");

cvSetMouseCallback("MyWindow",myMouseCallback,(void*)img);
cvShowImage("MyWindow",img);
cvWaitKey(0);
cvDestroyAllWindows();
cvReleaseImage(&img);
return 0;
}