OpenCV-How to rotate captured video from camera

Question

I have OpenCV project using C language. I wish to rotate the captured video from camera, how I can do that? What is the rotate function in OpenCV? My code as below

static CvCapture * cap;

cap = cvCaptureFromCAM(cam_index);

Flip(cap, 0);

But it got error. How I can rotate my video? Please help

Just use `cvWarpAffine` https://docs.opencv.org/2.4/modules/imgproc/doc/geometric_transformations.html?#warpaffine, I guest :) — tuan.tran, Jun 22 '18 at 03:33
I'm able to flip it now, just it only flip 180 degree. Not able to flip 90 degree. How I can flip 90 degree. — Bubble Bub, Jun 22 '18 at 08:27
@TuấnTrầnDuy do you have any similar project in C language can share for me as reference? Thanks — Bubble Bub, Jun 24 '18 at 07:53
@DerickLoo It's just some simple lines code. You can refer https://stackoverflow.com/a/15043287/5832644 — tuan.tran, Jun 24 '18 at 14:46

fireant · Answer 1 · 2018-06-24T17:56:31.573

0

You would rotate the video frame by frame. First, using getRotationMatrix2D() you get the rotation matrix, then using warpAffine() rotate each frame.

Mat image = imread("test.jpg");
Mat rot = getRotationMatrix2D(Point2f(image.cols/2.0, image.rows/2.0), angle, 1.0);
Mat rotated;
warpAffine(image, rotated, rot, image.size());

edited Jun 24 '18 at 17:56

answered Jun 22 '18 at 04:39

fireant

14,080
4
39
48

How I can use this 2 function in C language? Any similar project in C language can share to me as reference? Thanks a lot. – Bubble Bub Jun 22 '18 at 09:47
@DerickLoo see the code snippet I've added to the answer. – fireant Jun 24 '18 at 17:56

OpenCV-How to rotate captured video from camera

1 Answers1