opencv显示鼠标所在位置的rgb值

#include"highgui.h"
#include"cv.h"
#include"cxcore.h"
#include<stdlib.h>
void dispplex(IplImage*img,char*var1,char*var2 , char* var3,int x,int y)
{
	CvFont font;
	cvInitFont(&font,CV_FONT_HERSHEY_SCRIPT_COMPLEX,1.0,1.0);
	cvPutText(img,var1,cvPoint(x,y),&font,cvScalar(255,255,0));
	cvPutText(img,var2,cvPoint(x+100,y),&font,cvScalar(255,255,0));
	cvPutText(img,var3,cvPoint(x+200,y),&font,cvScalar(255,255,0));
	cvShowImage("demo",img);

}
void cvmovecallback(int event,int x,int y,int flags,void*para)
{
	IplImage*img=(IplImage*)para;
	switch(event){
	case CV_EVENT_LBUTTONDOWN:
		{
			uchar *rgb;
			rgb=(uchar*)(img->imageData+y*(img->widthStep)+(img->nChannels)*x);
			char var1[5];
				itoa((int)rgb[1],var1,10);
			char var2[5];
				itoa((int)rgb[2],var2,10);
				char var3[5];
				itoa((int)rgb[3],var3,10);
			dispplex(img,var1,var2,var3,x,y);
		break;
		}
	default:break;
	}
}
int main(int agrc,char**argv)
{
	IplImage *img=cvLoadImage("adc.jpg");
	int x=0;
	int y=0;
	cvNamedWindow("demo");
	cvSetMouseCallback("demo",cvmovecallback,(void*)img);
	cvShowImage("demo",img);

	cvWaitKey(0);

}