OpenCV——Skewing

// define head function
#ifndef PS_ALGORITHM_H_INCLUDED
#define PS_ALGORITHM_H_INCLUDED

#include <iostream>
#include <string>
#include "cv.h"
#include "highgui.h"
#include "cxmat.hpp"
#include "cxcore.hpp"
#include "math.h"

using namespace std;
using namespace cv;

void Show_Image(Mat&, const string &);

#endif // PS_ALGORITHM_H_INCLUDED

#include "PS_Algorithm.h"
#include <time.h>

using namespace std;
using namespace cv;

#define pi 3.1415926

int main()
{
string Img_name("4.jpg");
Mat Img;
Img=imread(Img_name);

float theta=pi/6;

int width=Img.cols;
int height=Img.rows;

/*
// horizontal skewing
int new_height=height;
int new_width=width+height*tan(theta)+1;
Mat Img_H=Mat::zeros(new_height,new_width, CV_8UC3);

float Dis;
float new_x, new_y;
float x1, y1, p;
for (int y=0; y<new_height; y++)
{
Dis=(height-y)*tan(theta);
for (int x=0; x<new_width; x++)
{
new_y=y;
// right skew
//  new_x=x-Dis;
// left skew
new_x=x+Dis-height*tan(theta);

// if (new_x<0) new_x=0;
// if (new_x>width-1) new_x=width-2;

if (new_x>0 && new_x<width-1)
{
x1=int(new_x);
y1=int(new_y);
p=new_x-x1;

Img_H.at<Vec3b>(y,x)[0]=(1-p)*Img.at<Vec3b>(y1,x1)[0]+p*Img.at<Vec3b>(y1,x1+1)[0];
Img_H.at<Vec3b>(y,x)[1]=(1-p)*Img.at<Vec3b>(y1,x1)[1]+p*Img.at<Vec3b>(y1,x1+1)[1];
Img_H.at<Vec3b>(y,x)[2]=(1-p)*Img.at<Vec3b>(y1,x1)[2]+p*Img.at<Vec3b>(y1,x1+1)[2];

}

}
}
Show_Image(Img_H, "out");
imwrite("H.jpg", Img_H);
*/

// vertical skewing
int new_height=height+width*tan(theta)+1;
int new_width=width;
Mat Img_V=Mat::zeros(new_height,new_width, CV_8UC3);

float Dis;
float new_x, new_y;
float x1, y1, p;
for (int y=0; y<new_height; y++)
{

for (int x=0; x<new_width; x++)
{
Dis=x*tan(theta);
new_x=x;
// right skew
new_y=y-Dis;
// left skew
//  new_y=y+Dis-width*tan(theta);

if (new_y>0 && new_y<height-1)
{
x1=int(new_x);
y1=int(new_y);
p=new_y-y1;

Img_V.at<Vec3b>(y,x)[0]=(1-p)*Img.at<Vec3b>(y1,x1)[0]+p*Img.at<Vec3b>(y1+1,x1)[0];
Img_V.at<Vec3b>(y,x)[1]=(1-p)*Img.at<Vec3b>(y1,x1)[1]+p*Img.at<Vec3b>(y1+1,x1)[1];
Img_V.at<Vec3b>(y,x)[2]=(1-p)*Img.at<Vec3b>(y1,x1)[2]+p*Img.at<Vec3b>(y1+1,x1)[2];

}

}
}
Show_Image(Img_V, "out");
imwrite("V.jpg", Img_V);

waitKey();

}

// define the show image
#include "PS_Algorithm.h"
#include <iostream>
#include <string>

using namespace std;
using namespace cv;

void Show_Image(Mat& Image, const string& str)
{
namedWindow(str.c_str(),CV_WINDOW_AUTOSIZE);
imshow(str.c_str(), Image);

}