How to Rotate and/or Flip (Mirror) Images in OpenCV

In this post I’m sharing a couple of very simple tricks to perform an efficient Rotate or Flip (Mirror) operation on OpenCV Mat images.

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Obviously you’ll start by reading an image from disk, or grab it from a video frame and so on, similar to this:

imread("/Users/amin/Test.jpg");

After that depending on the required transformation use any of the following codes.

Flip (Mirror) Vertically

flip(image, image, 0);

Flip (Mirror) Horizontally

flip(image, image, +1);

Rotate 90 Degrees Clockwise

transpose(image, image);
flip(image, image, +1);

Rotate 90 Degrees Counter Clockwise (Same as -90 Degrees and 270 Degrees)

transpose(image, image);
flip(image, image, 0);

Rotate 180 Degrees (Same as Flipping vertically and horizontally at the same time)

flip(image, image, -1);

Post your comments and questions below.

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