截图一部分图片 保存车辆特征

vector::const_iterator iter;
for(iter=cars.begin();iter!=cars.end();iter++)
{
rectangle(frame,cvPoint(cvRound(iter->x*scale),cvRound(iter->y*scale)),
CvPoint(cvRound((iter->x+iter->width)*scale),cvRound((iter->y+iter->height)*scale)),
Scalar(0,0,0),2,8);
int width = abs(cvRound(iter->x*scale) - cvRound((iter->x+iter->width)*scale));//绝对值
int height = abs(cvRound(iter->y*scale) - cvRound((iter->y+iter->height)*scale));
if (width == 0 || height == 0)
{
printf("width == 0 || height == 0");
return;
}
if (timeNum == 0)
{
Mat dst = old(Rect(min(cvRound(iter->x*scale),cvRound((iter->x+iter->width)*scale)),min(cvRound(iter->y*scale),cvRound((iter->y+iter->height)*scale)),width,height));//不知道原理

QDateTime time = QDateTime::currentDateTime(); //获取系统现在的时间
QString fileRoot =CAR_FEATURE;
//判断路径是否存在，不存在就创建
QDir dir(fileRoot);
if(!dir.exists())
{
dir.mkdir(fileRoot);
}
QString name = fileRoot + time.toString("yyyyMMddhhmmss")+QString::number(carNum++)+"_cartest.jpg";
imwrite(name.toLatin1().data(),dst);
}