图像旋转算法的实现

来源：互联网发布：vnr网络连接不畅编辑：程序博客网时间：2024/04/26 18:03

上一篇转载的文章（http://blog.csdn.net/carson2005/article/details/36900161）介绍了图像旋转的原理，这里给出代码实现，具体原理请参考上面的链接；

实现代码：

void ImgRotate(cv::Mat imgIn, float theta, cv::Mat& imgOut){int oldWidth = imgIn.cols;int oldHeight = imgIn.rows;// 源图四个角的坐标（以图像中心为坐标系原点）float fSrcX1,fSrcY1,fSrcX2,fSrcY2,fSrcX3,fSrcY3,fSrcX4,fSrcY4;fSrcX1 = (float) (- (oldWidth  - 1) / 2);fSrcY1 = (float) (  (oldHeight - 1) / 2);fSrcX2 = (float) (  (oldWidth  - 1) / 2);fSrcY2 = (float) (  (oldHeight - 1) / 2);fSrcX3 = (float) (- (oldWidth  - 1) / 2);fSrcY3 = (float) (- (oldHeight - 1) / 2);fSrcX4 = (float) (  (oldWidth  - 1) / 2);fSrcY4 = (float) (- (oldHeight - 1) / 2);// 旋转后四个角的坐标（以图像中心为坐标系原点）float fDstX1,fDstY1,fDstX2,fDstY2,fDstX3,fDstY3,fDstX4,fDstY4;fDstX1 =  cos(theta) * fSrcX1 + sin(theta) * fSrcY1;fDstY1 = -sin(theta) * fSrcX1 + cos(theta) * fSrcY1;fDstX2 =  cos(theta) * fSrcX2 + sin(theta) * fSrcY2;fDstY2 = -sin(theta) * fSrcX2 + cos(theta) * fSrcY2;fDstX3 =  cos(theta) * fSrcX3 + sin(theta) * fSrcY3;fDstY3 = -sin(theta) * fSrcX3 + cos(theta) * fSrcY3;fDstX4 =  cos(theta) * fSrcX4 + sin(theta) * fSrcY4;fDstY4 = -sin(theta) * fSrcX4 + cos(theta) * fSrcY4;int newWidth  = ( max( fabs(fDstX4 - fDstX1), fabs(fDstX3 - fDstX2) ) + 0.5);int newHeight = ( max( fabs(fDstY4 - fDstY1), fabs(fDstY3 - fDstY2) )  + 0.5);imgOut.create(newHeight, newWidth, imgIn.type());float dx = -0.5*newWidth*cos(theta) - 0.5*newHeight*sin(theta) + 0.5*oldWidth;float dy = 0.5*newWidth*sin(theta) - 0.5*newHeight*cos(theta) + 0.5*oldHeight;int x,y;for (int i=0; i<newHeight; i++){for (int j=0; j<newWidth; j++){x = float(j)*cos(theta) + float(i)*sin(theta) + dx;y = float(-j)*sin(theta) + float(i)*cos(theta) + dy;if ((x<0) || (x>=oldWidth) || (y<0) || (y>=oldHeight)){if (imgIn.channels() == 3){imgOut.at<cv::Vec3b>(i,j) = cv::Vec3b(0,0,0);}else if (imgIn.channels() == 1){imgOut.at<uchar>(i,j) = 0;}}else{if (imgIn.channels() == 3){imgOut.at<cv::Vec3b>(i,j) = imgIn.at<cv::Vec3b>(y,x);}else if (imgIn.channels() == 1){imgOut.at<uchar>(i,j) = imgIn.at<uchar>(y,x);}}}}}

测试代码：

void ImgRotateTest(){cv::Mat srcImg = cv::imread("test.jpg");if (srcImg.empty()){printf("srcImg load error \n");system("pause");exit(-1);}float angle = 30.0f*3.1415926/180.0f;cv::Mat dstImg;ImgRotate(srcImg, angle, dstImg);cv::imwrite("result.jpg", dstImg);cv::imshow("src", srcImg);cv::imshow("dst", dstImg);cv::waitKey(0);}

测试结果：

2 0