c++实现图像变化大小的实现

参考：https://blog.youkuaiyun.com/jizhidexiaoming/article/details/80306677

                     

#include <opencv2/opencv.hpp>
using namespace cv;
 
Mat my_resize(const Mat &, int, int);
 
int main()
{
	Mat img = imread("D:/Code/Image/classic.jpg", 0);
	imshow("原图", img);
 
	Mat new_img = my_resize(img, 200, 100); // (width, height)，(col, row)
	imshow("缩放后效果", new_img);
	waitKey(0);
	return 0;
}
 
Mat my_resize(const Mat &img, int width, int height)
{
	// 1, 定义缩放后的图像大小，行列缩放比例
	Mat output = Mat::zeros(Size(width, height), CV_8UC1);
	float width_scale = (float)img.cols / width;     // 列缩放比例，相对于算法前面讲的k1
	float height_scale = (float)img.rows / height;   // 行缩放比例，即k2
 
	// 2, 采样
	for (int i = 0; i < height; i++)  // 注意i,j的范围, i < height * img.rows / height;
	{
		for (int j = 0; j < width; j++)  
		{
			output.at<uchar>(i, j) = img.at<uchar>(round(i * height_scale), round(j * width_scale));
		}
	}
 
	return output;
 
}