Opencv 任意比例旋转图像

本文转自：http://blog.sina.com.cn/s/blog_400b87c20100cdr4.html

最关键的设置是：cvMat 2行3列的矩阵的值，这是就是计算机图形学里面的变换矩阵。具体见帮助手册 cvGetQuadrangleSubPix 词条

<span style="font-size:18px;">void CCannyDoc::OnConvert()
{
//声明IplImage指针
IplImage * src = NULL;
IplImage * dst = NULL;

src = cvLoadImage(i,-1);
int delta = 1;
int angle = 0;
int opt = 1; // 1：旋转加缩放,0: 仅仅旋转
double factor;
dst = cvCloneImage (src); //这里是通过函数来对dst初始化，直接“dst=src”可能导致浅拷贝
cvNamedWindow ("src", 1);
cvShowImage ("src", src);

for (;;)
{
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 = src->width;
int h = src->height;
if (opt) // 旋转加缩放，用到了cos肯定是循环变化
factor = (cos (angle * CV_PI / 180.) + 1.0) * 2;
else // 仅仅旋转，每次增加一个angle值
factor = 1;
m[0] = (float) (factor * cos (-angle * 2 * CV_PI / 180.));
m[1] = (float) (factor * sin (-angle * 2 * CV_PI / 180.));
m[3] = -m[1];
m[4] = m[0];
// 将旋转中心移至图像中间
m[2] = w * 0.5f;
m[5] = h * 0.5f;
// dst(x,y) = A * src(x,y) + b
cvZero (dst); //将dst区域全部赋给空值
cvGetQuadrangleSubPix (src, dst, &M);
cvNamedWindow ("dst", 1);
cvShowImage ("dst", dst);

if (cvWaitKey (1) == 27) //ESC
break;
angle = (int) (angle + delta) % 360;
}
}</span>

另一个连接也很详细：http://www.cnblogs.com/HappyXie/archive/2011/03/02/1969434.html