opencv常用函数

• getPerspectiveTransform和perspectiveTransform

getPerspectiveTransform和perspectiveTransform

getPerspectiveTransform和perspectiveTransform函数配合使用，目的是获取经过变化矩阵的图片

Mat getPerspectiveTransform(const Point2f src[], const Point2f dst[]) 

输入是原图和对应图点的xy坐标

void perspectiveTransform(InputArray src, OutputArray dst, InputArray m) 

输入是原图坐标和getPerspectiveTransform函数的输出，输入是对应的转化图的坐标点

int main( )
{
	Mat img=imread("boy.png");
	int img_height = img.rows;
	int img_width = img.cols;
	vector<Point2f> corners(4);
	corners[0] = Point2f(0,0);
	corners[1] = Point2f(img_width-1,0);
	corners[2] = Point2f(0,img_height-1);
	corners[3] = Point2f(img_width-1,img_height-1);
	vector<Point2f> corners_trans(4);
	corners_trans[0] = Point2f(150,250);
	corners_trans[1] = Point2f(771,0);
	corners_trans[2] = Point2f(0,img_height-1);
	corners_trans[3] = Point2f(650,img_height-1);
 
	Mat transform = getPerspectiveTransform(corners,corners_trans);
	cout<<transform<<endl;
	vector<Point2f> ponits, points_trans;
	for(int i=0;i<img_height;i++){
		for(int j=0;j<img_width;j++){
			ponits.push_back(Point2f(j,i));
		}
	}
 
	perspectiveTransform( ponits, points_trans, transform);
	Mat img_trans = Mat::zeros(img_height,img_width,CV_8UC3);
	int count = 0;
	for(int i=0;i<img_height;i++){
		uchar* p = img.ptr<uchar>(i);
		for(int j=0;j<img_width;j++){
			int y = points_trans[count].y;
			int x = points_trans[count].x;
			uchar* t = img_trans.ptr<uchar>(y);
			t[x*3]  = p[j*3];
			t[x*3+1]  = p[j*3+1];
			t[x*3+2]  = p[j*3+2];
			count++;
		}
	}
	imwrite("boy_trans.png",img_trans);
 
	return 0;
}```