openCv 图像顺时针、逆时针旋转

通过下面这个函数调用

Rotate90(workImg,270); //顺时针旋转

Rotate90(workImg,90); //逆时针旋转

实现，其实用该函数旋转任意度数对正方形图都ok，只是长方形图旋转后会有拉伸部分，不好掌握新图的长宽。

void Rotate90(IplImage *workImg,int angle)
{
    int opt = 0;                            //  1: 加缩放   0: 仅旋转
    double factor;                          //  缩放因子
    IplImage *pImage;
    IplImage *pImgRotation = NULL;

    pImage = workImg;
    pImgRotation = cvCloneImage(workImg);

    angle=-angle;

    //  创建 M 矩阵
    float m[6];
    //      Matrix m looks like:
    //      [ m0  m1  m2 ] ----> [ a11  a12  b1 ]
    //      [ m3  m4  m5 ] ----> [ a21  a22  b2 ]

    CvMat M = cvMat(2,3,CV_32F,m);
    int w = workImg->height;
    int h = workImg->width;

    if (opt) factor = (cos(angle*CV_PI/180.)+1.0)*2;
    else factor = 1;

    m[0] = (float)(factor*cos(-angle*CV_PI/180.));
    m[1] = (float)(factor*sin(-angle*CV_PI/180.));
    m[3] = -m[1];
    m[4] =  m[0];
    //  将旋转中心移至图像中心
    m[2] = w*0.5f;
    m[5] = h*0.5f;

    //---------------------------------------------------------
    //  dst(x,y) = A * src(x,y) + b
    cvZero(pImgRotation);
    cvGetQuadrangleSubPix(pImage,pImgRotation,&M);
    //---------------------------------------------------------

    cvNamedWindow("Rotation Image");
    cvFlip(pImgRotation);
    cvShowImage("Rotation Image",pImgRotation);

    cvReleaseImage( &pImgRotation );
    cvWaitKey(0);

    cvDestroyWindow("Rotation Image");
}

from: http://blog.csdn.net/abcjennifer/article/details/7269968