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

Here's my EmguCV (a C# port of OpenCV) solution:

public static Image Rotate90(this Image img)
    where TColor : struct, IColor
    where TDepth : new()
{
    var rot = new Image(img.Height, img.Width);
    CvInvoke.cvTranspose(img.Ptr, rot.Ptr);
    rot._Flip(FLIP.HORIZONTAL);
    return rot;
}

public static Image Rotate180(this Image img)
    where TColor : struct, IColor
    where TDepth : new()
{
    var rot = img.CopyBlank();
    rot = img.Flip(FLIP.VERTICAL);
    rot._Flip(FLIP.HORIZONTAL);
    return rot;
}

public static void _Rotate180(this Image img)
    where TColor : struct, IColor
    where TDepth : new()
{
    img._Flip(FLIP.VERTICAL);
    img._Flip(FLIP.HORIZONTAL);
}

public static Image Rotate270(this Image img)
    where TColor : struct, IColor
    where TDepth : new()
{
    var rot = new Image(img.Height, img.Width);
    CvInvoke.cvTranspose(img.Ptr, rot.Ptr);
    rot._Flip(FLIP.VERTICAL);
    return rot;
}

Shouldn't be too hard to translate it back into C++.