opencv学习-像素重映射

Posted 2021-08-05 殇堼

API-remap

remap(src, dst, map_x, map_y, INTER_LINEAR, BORDER_CONSTANT, Scalar(0, 0, 255));

单个案例代码-向X轴做对称

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

using namespace cv;

int main()
{
	Mat src, dst;
	Mat map_x, map_y;
	src = imread("D:/images/lena.png");
	if (src.empty())
	{
		printf("读取文件错误，请确定目录下是否有imread函数~！\\n");
		return -1;
	}
	
	imshow("【原图】", src);

	//创建效果图，x重映射图，y重映射图
	dst.create(src.size(), src.type());
	map_x.create(src.size(), CV_32FC1);
	map_y.create(src.size(), CV_32FC1);

	//双层循环，遍历每一个像素点，改变map_x,map_y的值

	for (int j = 0; j < src.rows; j++)
	{
		for (int i = 0; i < src.cols; i++)
		{
			map_x.at<float>(j, i) = static_cast<float>(i);//横坐标保持不变
			map_y.at<float>(j, i) = static_cast<float>(src.rows - j);//纵坐标取反
		}
	}
	//进行重映射
	remap(src, dst, map_x, map_y, INTER_LINEAR, BORDER_CONSTANT, Scalar(0, 0, 255));

	//显示效果图
	imshow("【程序窗口】", dst);
	waitKey();
	return 0;
}

代码展示

#define INPUT_TITLE "input image"
#define OUTPUT_TITLE "remap image"

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

using namespace std;
using namespace cv;

Mat img, src;//img 输入图像 ; src 最终输出的图像
Mat map_x, map_y;
int index = 0;
void updata_map();

int main() {

	img = imread("D:/images/lena.png");
	if (!img.data)
	{
		cout << "ERROR : could not load image.";
		return -1;
	}
	namedWindow(INPUT_TITLE, WINDOW_AUTOSIZE);
	namedWindow(OUTPUT_TITLE, WINDOW_AUTOSIZE);

	imshow(INPUT_TITLE, img);

	//建立映射表
	map_x.create(img.size(), CV_32FC1);
	map_y.create(img.size(), CV_32FC1);

	int c = 0;
	while (true)
	{
		c = waitKey(500);
		index = c % 4;
		if ((char)c == 27)
		{
			break;
		}
		updata_map();
		remap(img, src, map_x, map_y, INTER_LINEAR, BORDER_CONSTANT, Scalar(0, 0, 255));
		imshow(OUTPUT_TITLE, src);
	}


	return 0;
}

void updata_map() {
	for (int row = 0; row < img.rows; row++)
	{
		for (int col = 0; col < img.cols; col++)
		{
			switch (index)
			{
				//index = 0 ，图像的行跟列为为原来的1/2。
				//index = 1，为左右翻转（列变换，行不变）
				//index = 2，为上下翻转（行变换，列不变）
				//index = 3，为中心旋转

			case 0:
				if (col >(img.cols*0.25) && col<(img.cols*0.75) && row>(img.rows*0.25) && row < (img.rows*0.75)) {
					map_x.at<float>(row, col) = 2 * (col - (img.cols*0.25));
					map_y.at<float>(row, col) = 2 * (row - (img.rows*0.25) - 0.25);
				}
				else
				{
					map_x.at<float>(row, col) = 0;
					map_y.at<float>(row, col) = 0;
				}
				break;
			case 1:
				map_x.at<float>(row, col) = (img.cols - col - 1);
				map_y.at<float>(row, col) = row;
				break;
			case 2:
				map_x.at<float>(row, col) = col;
				map_y.at<float>(row, col) = (img.rows - row - 1);
				break;
			case 3:
				map_x.at<float>(row, col) = (img.cols - col - 1);
				map_y.at<float>(row, col) = (img.rows - row - 1);
				break;

			default:
				break;
			}
		}
	}
}