将 Opencv 矩阵旋转 90、180、270 度

问题描述

我正在从网络摄像头捕获图像，我需要将其旋转直角.我发现自己有这些功能:

I'm capturing image from webcam and I need to rotate it by right angle. I found myself theese functions:

1. getRotationMatrix2D - 创建旋转矩阵(不管它是什么)
2. transform - 通过旋转矩阵将一个矩阵转换为另一个矩阵

1. getRotationMatrix2D - to create rotation matrix (whatever it is)
2. transform - transform one matrix to another by rotation matrix

但是，除了黑色区域，我什么也没有.这是我的代码:

But, I don't get anything but black area. This is my code:

   if(rotate_button.click%4>0) {
       double angle = (rotate_button.click%4)*90;  //button increments its click by 1 per click
       Mat transform_m = getRotationMatrix2D(Point(cam_frame_width/2, cam_frame_height/2), angle, 1);  //Creating rotation matrix
       Mat current_frame;
       transform(cam_frame, current_frame, transform_m);  //Transforming captured image into a new one
       cam_frame = Mat((int)current_frame.cols,(int)current_frame.rows, cam_frame_type) = Scalar(0,128,0);  //resizing captured matrix, so I can copy the resized one on it
       current_frame.copyTo(cam_frame);  //Copy resized to original
   }

输出只是黑屏.

推荐答案

Use warpAffine.:

Use warpAffine.:

试试:

Point2f src_center(source.cols/2.0F, source.rows/2.0F);
Mat rot_mat = getRotationMatrix2D(src_center, angle, 1.0);
Mat dst;
warpAffine(source, dst, rot_mat, source.size());

dst 是最终图像

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