Rotating back points from a rotated image in OpenCV

Question

I’m having troubles with rotation. What I want to do is this:

• Rotate an image
• Detect features on the rotated image (points)
• Rotate back the p

Answer 1

• You need to rotate your points accorning to center point of your image.
• Here x and y are your points which you want to rotate, imageCenter_x aand _y is center point of your image.

• Below is my code.

  angle = angle * (M_PI / 180);  
  float axis_x = x - imageCenter_x;  
  float axis_y = y - imageCenter_y;       
  
  x = axis_x * cos(angle) + axis_y * sin(angle);   
  y = (-axis_x) * sin(angle) + axis_y * cos(angle);
  
  x = x + imageCenter_x;  
  y = y + imageCenter_y;