Easiest way to rotate by 90 degrees an image using OpenCV?

Question

What is the best way (in c/c++) to rotate an IplImage/cv::Mat by 90 degrees? I would assume that there must be something better than transforming it using a matrix, but I ca

Answer 1

Update for transposition:

You should use cvTranspose() or cv::transpose() because (as you rightly pointed out) it's more efficient. Again, I recommend upgrading to OpenCV2.0 since most of the cvXXX functions just convert IplImage* structures to Mat objects (no deep copies). If you stored the image in a Mat object, Mat.t() would return the transpose.

Any rotation:

You should use cvWarpAffine by defining the rotation matrix in the general framework of the transformation matrix. I would highly recommend upgrading to OpenCV2.0 which has several features as well as a Mat class which encapsulates matrices and images. With 2.0 you can use warpAffine to the above.