最近在做项目需要把把图片绕图片中任意点旋转任意角度，考虑到自己旋转需要编写插值算法，所以想到了用opencv，但是网上都是围绕图片中点旋转任意角度的，都是向下面这样写的：
绕图片中心旋转图片不裁剪
#include"opencv.hpp"
#include<iostream>
using namespace std;
using namespace cv;
int main() {
Mat src = imread("timg.jpg");
Mat des,m;
Point2f center = Point(src.cols / 2, src.rows / 2);
double angle = 50,scale=0.5;
int w = src.cols, h = src.rows;
int bound_w = (h * fabs(sin(angle * CV_PI / 180)) + w * fabs(cos(angle * CV_PI / 180))) * scale;
int bound_h = (h * fabs(cos(angle * CV_PI / 180)) + w * fabs(sin(angle * CV_PI / 180))) * scale;
m = getRotationMatrix2D(center, angle, scale);
m.at<double>(0, 2) += (bound_w - src.cols) / 2;
m.at<double>(1, 2) += (bound_h - src.rows) / 2;
warpAffine(src,des,m,Size2i(bound_h,bound_w));
imshow("image",des);
waitKey();
return 0;旋转之后的效果:
但是遇到绕任意点旋转时，会产生问题，用这种方式还是会存在裁剪，如果要理解绕任意点旋转，需要先理解函数getRotationMatrix2D，这个函数处理过程如下面矩阵表示所示：
具体实现代码如下：
Mat src = imread("/home/sss/1111.jpg", IMREAD_GRAYSCALE);
Mat des, m;
//旋转的任意角度
double angle = 45;
int w = src.cols, h = src.rows;
Point2f rorate_center;
//旋转的任意中心
rorate_center.x = w;
rorate_center.y = h;
//重新计算旋转后的宽和高
int bound_w = ceil(h * fabs(sin(angle * CV_PI / 180.0)) + w * fabs(cos(angle * CV_PI / 180.0)));
int bound_h = ceil(h * fabs(cos(angle * CV_PI / 180.0)) + w * fabs(sin(angle * CV_PI / 180.0)));
m = getRotationMatrix2D(rorate_center, angle, 1.0);
//通过eigen计算旋转矩阵
Eigen::Matrix3d T1;
T1 << 1, 0, -rorate_center.x,
0, 1, -rorate_center.y,
0, 0, 1;
Eigen::Matrix3d T2;
T2 << 1, 0, rorate_center.x,
0, 1, rorate_center.y,
0, 0, 1;
Eigen::Matrix3d rorate;
rorate << cos(angle * CV_PI / 180.0), sin(angle * CV_PI / 180.0), 0,
-sin(angle * CV_PI / 180.0), cos(angle * CV_PI / 180.0), 0,
0, 0, 1;
Eigen::Matrix3d T = T2 * rorate * T1;
//计算原来矩阵的四个顶点经过变换后的顶点
Eigen::Matrix<double,3, 1> left_top_p, right_top_p, right_bottom_p, left_botoom_p;
left_top_p << 0, 0, 1;
right_top_p << w, 0, 1;
right_bottom_p << w, h, 1;
left_botoom_p << 0, h , 1;
left_top_p = T * left_top_p;
right_top_p = T * right_top_p;
right_bottom_p = T * right_bottom_p;
left_botoom_p = T * left_botoom_p;
//找到经过变换过定位的最大最小值
double min_x = 10000, min_y = 10000;
//min_x
if(left_top_p[0] < min_x){
min_x = left_top_p[0];
}
if(right_top_p[0] < min_x){
min_x = right_top_p[0];
}
if(right_bottom_p[0] < min_x)
{
min_x = right_bottom_p[0];
}
if(left_botoom_p[0] < min_x){
min_x = left_botoom_p[0];
}
//min_y
if(left_top_p[1] < min_y){
min_y = left_top_p[1];
}
if(right_top_p[1] < min_y){
min_y = right_top_p[1];
}
if(right_bottom_p[1] < min_y)
{
min_y = right_bottom_p[1];
}
if(left_botoom_p[1] < min_y){
min_y = left_botoom_p[1];
}
double max_x = -1000, max_y = -1000;
//max_x
if(left_top_p[0] > max_x){
max_x = left_top_p[0];
}
if(right_top_p[0] > max_x){
max_x = right_top_p[0];
}
if(right_bottom_p[0] > max_x)
{
max_x = right_bottom_p[0];
}
if(left_botoom_p[0] > max_x){
max_x = left_botoom_p[0];
}
//max_y
if(left_top_p[1] > max_y){
max_y = left_top_p[1];
}
if(right_top_p[1] > max_y){
max_y = right_top_p[1];
}
if(right_bottom_p[1] > max_y)
{
max_y = right_bottom_p[1];
}
if(left_botoom_p[1] > max_y){
max_y = left_botoom_p[1];
}
//将偏置添加到矩阵中
m.at<double>(0, 2) += -min_x;
m.at<double>(1, 2) += -min_y;
//变换，最后不会存在裁剪
warpAffine(src, des , m , Size2i(bound_w , bound_h),
INTER_LINEAR, 0, Scalar(100, 100, 100));
imwrite("/home/sss/222.jpg", des);
return 0;经过变换过的图片不会存在裁剪：
到此这篇关于OpenCV实现绕图片中任意角度旋转任意角度的文章就介绍到这了,更多相关OpenCV图片旋转内容请搜索编程网以前的文章或继续浏览下面的相关文章希望大家以后多多支持编程网！
