Remapping

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#include <opencv2/opencv.hpp>
#include <iostream>

using namespace cv;
using namespace std;

void updata_map(int& ind, Mat& map_x,Mat& map_y);

Mat src;


int main(void)
{
	src = imread("../res/beauty.jpg",cv::IMREAD_COLOR);
	if(src.empty())
	{
		cout << "can't load image,please confirm your path"<< endl; 
	}

	Mat dst(src.size(),src.type());
	Mat map_x(src.size(), CV_32FC1); //x方向的映射关系
	Mat map_y(src.size(), CV_32FC1);//y方向的映射关系

	const char* window_name = "Remapping Demo" ;
	namedWindow(window_name, cv::WINDOW_AUTOSIZE);

	int ind =0;
	for(;;)
	{
		updata_map(ind,map_x,map_y); //更新映射关系
		remap(src,dst,map_x,map_y,cv::INTER_LINEAR,cv::BORDER_CONSTANT,Scalar(0,0,0));
		imshow(window_name,dst);

		char c = (char)waitKey(1000);
		if(c == 27)
		{
			break;
		}
	}	
	
	return 0;
};


void updata_map(int& ind, Mat& map_x,Mat& map_y)
{
	for(int i=0; i<src.rows; i++)
		for(int j=0; j<src.cols; j++)
		{
			switch(ind)
			{
				case 0:
					if(i>src.rows*0.25 && i<src.rows*0.75 && j>src.cols*0.25 && j<src.cols*0.75) //在中间
					{
						map_x.at<float>(i,j) = 2*j-0.5*src.cols+0.5; //x进行缩小一半 见 下面图的说明
						map_y.at<float>(i,j) = 2*i-0.5*src.rows+0.5;// x进行缩小一半 见 下面图的说明
					}
					else//没有映射关系
					{
						map_x.at<float>(i,j) = 0;
						map_y.at<float>(i,j) = 0;
					}
					break;
				case 1:
					map_x.at<float>(i,j) = j;
					map_y.at<float>(i,j) =src.rows-i; //y方向翻转
					break;
				case 2:
					map_x.at<float>(i,j) = src.cols-j; //x方向翻转
					map_y.at<float>(i,j) = i; 
					break;
				case 3:
					map_x.at<float>(i,j) = src.cols-j;  //x方向翻转
					map_y.at<float>(i,j) = src.rows-i; //y方向翻转
					break;
				default:
					break;

			}
		}
	ind = (ind+1)%4;
}