如何只保存一次相同的面

我正在做一个关于监控摄像头人脸检测的项目。现在我正处于人脸检测的阶段，我可以从每一帧中检测人脸。在检测到人脸后，我需要将该人脸存储到本地文件夹中。现在我可以将每个面保存在指定的文件夹中。

问题现在它正在保存每个面，但我只需要保存一次相同的面。这意味着，如果将一张人脸保存为jpeg图像，当人脸检测再次进行时，会出现同一张人脸，所以这次我不想保存那个特定的人脸。

这是我的代码：

#include <cv.h>   
#include <highgui.h>
#include <time.h>
#include <stdio.h>
using namespace std;
int ct=1;
int ct1=0;
IplImage *frame;
int frames;
void facedetect(IplImage* image);
void saveImage(IplImage *img,char *ex);
IplImage* resizeImage(const IplImage *origImg, int newWidth,int newHeight, bool    keepAspectRatio);
const char* cascade_name="haarcascade_frontalface_default.xml";
int k=1;
int main(int argc, char** argv)
{
CvCapture *capture=cvCaptureFromFile("Arnab Goswami on Pepper spary rajagopal        Complete NewsHour Debate (Mobile).3gp");
int count=1;
while(1)
{
frame = cvQueryFrame(capture);
if(count%30==0)
{   
facedetect(frame);
}
count++;    
}   
cvReleaseCapture(&capture);
return 0;
}
void facedetect(IplImage* image)
{
ct1++;
cvNamedWindow("output");
int j=0,i,count=0,l=0,strsize;
char numstr[50];
int arr[100],arr1[100];
CvPoint ul,lr,w,h,ul1,lr1;
CvRect *r;
//int i=0;
IplImage* image1;IplImage* tmpsize;IplImage* reimg;
CvHaarClassifierCascade* cascade=(CvHaarClassifierCascade*) cvLoad(cascade_name);
CvMemStorage* storage=cvCreateMemStorage(0);
const char *extract;
if(!cascade)
{
cout<<"Coulid not load classifier cascade"<<endl;
}
if(cascade)
{
CvSeq*faces=cvHaarDetectObjects(image,cascade,storage,1.1,1,CV_HAAR_DO_CANNY_PRUNING,cvSize(10,10));
//function used for detecting faces.o/p is list of detected faces.
for(int i=0;i<(faces ? faces->total : 0);i++)
{
string s1="im",re,rename,ex=".jpeg";
sprintf(numstr, "%d", k);
re = s1 + numstr;
rename=re+ex;
char *extract1=new char[rename.size()+1];
extract1[rename.size()]=0;
memcpy(extract1,rename.c_str(),rename.size());
//Copies the values of rename.size from the location pointed by source                                  //(rename.c_str)directly to the memory block pointed by destination(extract).
strsize=rename.size();
r=(CvRect*) cvGetSeqElem(faces,i);//draw rectangle outline around each image.
ul.x=r->x;
ul.y=r->y;
w.x=r->width;
h.y=r->height;
lr.x=(r->x + r->width);
lr.y=(r->y + r->height);
cvSetImageROI(image,cvRect(ul.x,ul.y,w.x,h.y));
image1=cvCreateImage(cvGetSize(image),image->depth,image->nChannels);
cvCopy(image, image1, NULL);
reimg=resizeImage(image1, 40, 40, true);
saveImage(reimg,extract1);
cvResetImageROI(image);
cvRectangle(image,ul,lr,CV_RGB(1,255,0),3,8,0);
j++,count++;
k++;
cout<<"frame"<<ct1<<" "<<"face"<<ct<<":"<<"x: "<<ul.x<<endl;
cout<<"frame"<<ct1<<" "<<"face"<<ct<<":"<<"y: "<<ul.y<<endl;
cout<<""<<endl;
ct++;
//cvShowImage("output",image);
}
//return image;
//cvNamedWindow("output");//creating a window.
cvShowImage("output",image);//showing resized image.
cvWaitKey(0);
}
}
void saveImage(IplImage *img,char *ex)
{
int i=0;
char path[255]="/home/athira/Image/OutputImage";
char *ext[200];
char buff[1000];
ext[i]=ex;
sprintf(buff,"%s/%s",path,ext[i]);//copy ext[i] to buff
strcat(path,buff);//concat path & buff
cvSaveImage(buff,img);
i++;
}