取反

#include  <iostream> 
#include <opencvcv.h>
#include <opencv2corecore.hpp>
#include <opencv2highguihighgui.hpp>
using namespace std ;
using namespace cv ;

int main(){
    Mat now=imread("girl.jpg") ;
    if(now.empty()){
         cout<<"Can't find !"<<endl ;
         return -1 ;
    }
    imshow("old!",now) ;
    waitKey(0) ;
    Mat re;;
    re.create(now.rows, now.cols, now.type()) ;
    for(int i=0;i<now.rows;i++)
        for(int j=0;j<now.cols;j++)
            for(int k=0;k<now.channels();k++){
                re.at<Vec3b>(i,j)[k]=255-now.at<Vec3b>(i,j)[k] ;    
            }
    imshow("new!",re) ;
    imwrite("girl3.jpg",re) ;
    waitKey(0) ;
    return 0 ;
}