web-dev-qa-db-fra.com

OpenCV: Comment faire pivoter iplimage?

J'ai besoin de faire pivoter une image par très petit angle, comme 1 à 5 degrés. -OPENCV Fournir un moyen simple de le faire? De lire des documents, je peux supposer que getfreffinetransform () devrait être impliqué, mais il n'y a pas d'exemple direct de faire quelque chose comme:

IplImage *rotateImage( IplImage *source, double angle);
image-manipulationopencv
25
user11323

Si vous utilisez OpenCV> 2.0 c'est aussi facile que

using namespace cv;

Mat rotateImage(const Mat& source, double angle)
{
    Point2f src_center(source.cols/2.0F, source.rows/2.0F);
    Mat rot_mat = getRotationMatrix2D(src_center, angle, 1.0);
    Mat dst;
    warpAffine(source, dst, rot_mat, source.size());
    return dst;
}

Remarque: L'angle est en degrés, pas de radians.

Voir la documentation d'interface C++ pour plus de détails et adaptez-la à votre guise:

43
Martin

EDIT: TO Down VOTEUR: Veuillez commenter la raison pour laquelle le vote a été testé et un code éprouvé? 

#include "cv.h"
#include "highgui.h"
#include "math.h"
int main( int argc, char** argv )
{
    IplImage* src = cvLoadImage("lena.jpg", 1);    
    IplImage* dst = cvCloneImage( src );

    int delta = 1;
    int angle = 0;
    int opt = 1;   // 1： rotate & zoom
               // 0:  rotate only
    double factor;
    cvNamedWindow("src", 1);
    cvShowImage("src", src);

    for(;;)
    {
    float m[6];
    CvMat M = cvMat(2, 3, CV_32F, m);
    int w = src->width;
    int h = src->height;

    if(opt)  
        factor = (cos(angle*CV_PI/180.) + 1.05) * 2;
    else 
        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];
    m[2] = w*0.5f;  
    m[5] = h*0.5f;  

    cvGetQuadrangleSubPix( src, dst, &M);
    cvNamedWindow("dst", 1);
    cvShowImage("dst", dst);
    if( cvWaitKey(1) == 27 )
        break;
    angle =(int)(angle + delta) % 360;
    }     
    return 0;
}

[~ # ~] Mise à jour [~ # ~] : Voir le code suivant pour la rotation à l'aide de Warpaffine https://code.google. COM/P/OPENCVJP-Sample/Source/Parcourir/Trunk/CPP/Affine2_CPP.CPP? R = 48

#include <cv.h>
#include <highgui.h>

using namespace cv;

int
main(int argc, char **argv)
{
  // (1)load a specified file as a 3-channel color image,
  //    set its ROI, and allocate a destination image
  const string imagename = argc > 1 ? argv[1] : "../image/building.png";
  Mat src_img = imread(imagename);
  if(!src_img.data)
    return -1;
  Mat dst_img = src_img.clone();

  // (2)set ROI
  Rect roi_rect(cvRound(src_img.cols*0.25), cvRound(src_img.rows*0.25), cvRound(src_img.cols*0.5), cvRound(src_img.rows*0.5));
  Mat src_roi(src_img, roi_rect);
  Mat dst_roi(dst_img, roi_rect);

  // (2)With specified three parameters (angle, rotation center, scale)
  //    calculate an affine transformation matrix by cv2DRotationMatrix
  double angle = -45.0, scale = 1.0;
  Point2d center(src_roi.cols*0.5, src_roi.rows*0.5);
  const Mat affine_matrix = getRotationMatrix2D( center, angle, scale );

  // (3)rotate the image by warpAffine taking the affine matrix
  warpAffine(src_roi, dst_roi, affine_matrix, dst_roi.size(), INTER_LINEAR, BORDER_CONSTANT, Scalar::all(255));

  // (4)show source and destination images with a rectangle indicating ROI
  rectangle(src_img, roi_rect.tl(), roi_rect.br(), Scalar(255,0,255), 2);

  namedWindow("src", CV_WINDOW_AUTOSIZE);
  namedWindow("dst", CV_WINDOW_AUTOSIZE);
  imshow("src", src_img);
  imshow("dst", dst_img);
  waitKey(0);

  return 0;
}
5
enthusiasticgeek

Vérifiez ma réponse à un problème similaire:

rotation d'une image en C/C++

Essentiellement, utilisez cvwarpaffine - J'ai décrit comment obtenir la matrice de transformation 2x3 de l'angle dans ma réponse précédente.

4
Jacob

Mise à jour de la réponse complète pour OpenCV 2.4 et plus

// ROTATE p by R
/**
 * Rotate p according to rotation matrix (from getRotationMatrix2D()) R
 * @param R     Rotation matrix from getRotationMatrix2D()
 * @param p     Point2f to rotate
 * @return      Returns rotated coordinates in a Point2f
 */
Point2f rotPoint(const Mat &R, const Point2f &p)
{
    Point2f rp;
    rp.x = (float)(R.at<double>(0,0)*p.x + R.at<double>(0,1)*p.y + R.at<double>(0,2));
    rp.y = (float)(R.at<double>(1,0)*p.x + R.at<double>(1,1)*p.y + R.at<double>(1,2));
    return rp;
}

//COMPUTE THE SIZE NEEDED TO LOSSLESSLY STORE A ROTATED IMAGE
/**
 * Return the size needed to contain bounding box bb when rotated by R
 * @param R     Rotation matrix from getRotationMatrix2D()
 * @param bb    bounding box rectangle to be rotated by R
 * @return      Size of image(width,height) that will compleley contain bb when rotated by R
 */
Size rotatedImageBB(const Mat &R, const Rect &bb)
{
    //Rotate the rectangle coordinates
    vector<Point2f> rp;
    rp.Push_back(rotPoint(R,Point2f(bb.x,bb.y)));
    rp.Push_back(rotPoint(R,Point2f(bb.x + bb.width,bb.y)));
    rp.Push_back(rotPoint(R,Point2f(bb.x + bb.width,bb.y+bb.height)));
    rp.Push_back(rotPoint(R,Point2f(bb.x,bb.y+bb.height)));
    //Find float bounding box r
    float x = rp[0].x;
    float y = rp[0].y;
    float left = x, right = x, up = y, down = y;
    for(int i = 1; i<4; ++i)
    {
        x = rp[i].x;
        y = rp[i].y;
        if(left > x) left = x;
        if(right < x) right = x;
        if(up > y) up = y;
        if(down < y) down = y;
    }
    int w = (int)(right - left + 0.5);
    int h = (int)(down - up + 0.5);
    return Size(w,h);
}

/**
 * Rotate region "fromroi" in image "fromI" a total of "angle" degrees and put it in "toI" if toI exists.
 * If toI doesn't exist, create it such that it will hold the entire rotated region. Return toI, rotated imge
 *   This will put the rotated fromroi piece of fromI into the toI image
 *
 * @param fromI     Input image to be rotated
 * @param toI       Output image if provided, (else if &toI = 0, it will create a Mat fill it with the rotated image roi, and return it).
 * @param fromroi   roi region in fromI to be rotated.
 * @param angle     Angle in degrees to rotate
 * @return          Rotated image (you can ignore if you passed in toI
 */
Mat rotateImage(const Mat &fromI, Mat *toI, const Rect &fromroi, double angle)
{
    //CHECK STUFF
    // you should protect against bad parameters here ... omitted ...

    //MAKE OR GET THE "toI" MATRIX
    Point2f cx((float)fromroi.x + (float)fromroi.width/2.0,fromroi.y +
               (float)fromroi.height/2.0);
    Mat R = getRotationMatrix2D(cx,angle,1);
    Mat rotI;
    if(toI)
        rotI = *toI;
    else
    {
        Size rs = rotatedImageBB(R, fromroi);
        rotI.create(rs,fromI.type());
    }

    //ADJUST FOR SHIFTS
    double wdiff = (double)((cx.x - rotI.cols/2.0));
    double hdiff = (double)((cx.y - rotI.rows/2.0));
    R.at<double>(0,2) -= wdiff; //Adjust the rotation point to the middle of the dst image
    R.at<double>(1,2) -= hdiff;

    //ROTATE
    warpAffine(fromI, rotI, R, rotI.size(), INTER_CUBIC, BORDER_CONSTANT, Scalar::all(0)); 

    //& OUT
    return(rotI);
}
3
user1270710