如何通过openCV模拟鱼眼镜头效果? [英] How to simulate fisheye lens effect by openCV?

问题描述

我正在寻找创建鱼眼镜头效果的方法，查看了openCV的文档，它似乎包含针对诸如鱼眼之类的径向变形的相机校准"功能.是否可以通过openCV模拟鱼眼失真?

I am looking for ways to create fisheye lens effect, looked at documentations for openCV, it looks like it contains Camera Calibration functions for radial distortions like fisheye. Is it possible to simulate fisheye distortion by openCV?

如果与openGL相比，可以通过openCV进行，哪一个会产生更好的结果?谢谢.

If it is possible to do it by openCV, comparing to openGL, which one will generate better results? Thanks.

推荐答案

我使用opencv创建了此应用.这是您所指的效果吗? 我基本上对Wikipedia的失真(光学)"上显示的公式进行了编码，如果需要的话，我可以显示代码

I created this app using opencv. Is this the effect you are referring to? I basically coded the formula shown on wikipedia's "Distortion(optics)" I can show the code if needed

更新: 好的，下面是使用opencv用c ++编写的实际代码(未记录，请随时寻求解释): 该程序将以下参数作为输入:| 输入图像 | | 输出图像 | | K，它控制失真量(通常尝试0.001附近的值) | | x畸变中心的坐标 | | 变形中心的y坐标 |

Update: OK, so below is the actual code written in c++ using opencv (not documented so feel free to ask for explanations): The program recieves as input the following parameter: |input image| |output image| |K which controlls amount of distortion (typically try values around 0.001)| |x coordinate of center of distortion| |y coordinate of center of distortion|

因此，程序的关键是双重 for 循环，该循环在结果图像上逐像素迭代，并使用径向失真公式在输入图像中寻找匹配的像素(这是通常完成图像变形的方式-也许可以通过从输出到输入的反投影来直观地应对).有一些细微之处与输出图像的比例有关(在此程序中，生成的图像与输入的大小相同)，除非您想了解更多细节，否则我不会涉及.

So the crux of the program is the double for loop which iterates pixel by pixel on the result image and looks for the matching pixel in the input image using the formula for radial distortion (this is the way image warping is generally done - perhaps counter intuitively by back-projection from output to input). There are some subtleties which have to do with the scale of the output image (in this program the resulting image is the same size as the input), and I won't get into it unless you want to get into more details.enjoy.

    #include <cv.h>
    #include <highgui.h>
    #include <math.h>
    #include <unistd.h>
    #include <getopt.h>
    #include <iostream>


    void sampleImage(const IplImage* arr, float idx0, float idx1, CvScalar& res)
    {
      if(idx0<0 || idx1<0 || idx0>(cvGetSize(arr).height-1) || idx1>(cvGetSize(arr).width-1)){
        res.val[0]=0;
        res.val[1]=0;
        res.val[2]=0;
        res.val[3]=0;
        return;
      }
      float idx0_fl=floor(idx0);
      float idx0_cl=ceil(idx0);
      float idx1_fl=floor(idx1);
      float idx1_cl=ceil(idx1);

      CvScalar s1=cvGet2D(arr,(int)idx0_fl,(int)idx1_fl);
      CvScalar s2=cvGet2D(arr,(int)idx0_fl,(int)idx1_cl);
      CvScalar s3=cvGet2D(arr,(int)idx0_cl,(int)idx1_cl);
      CvScalar s4=cvGet2D(arr,(int)idx0_cl,(int)idx1_fl);
      float x = idx0 - idx0_fl;
      float y = idx1 - idx1_fl;
      res.val[0]= s1.val[0]*(1-x)*(1-y) + s2.val[0]*(1-x)*y + s3.val[0]*x*y + s4.val[0]*x*(1-y);
      res.val[1]= s1.val[1]*(1-x)*(1-y) + s2.val[1]*(1-x)*y + s3.val[1]*x*y + s4.val[1]*x*(1-y);
      res.val[2]= s1.val[2]*(1-x)*(1-y) + s2.val[2]*(1-x)*y + s3.val[2]*x*y + s4.val[2]*x*(1-y);
      res.val[3]= s1.val[3]*(1-x)*(1-y) + s2.val[3]*(1-x)*y + s3.val[3]*x*y + s4.val[3]*x*(1-y);
    }

    float xscale;
    float yscale;
    float xshift;
    float yshift;

    float getRadialX(float x,float y,float cx,float cy,float k){
      x = (x*xscale+xshift);
      y = (y*yscale+yshift);
      float res = x+((x-cx)*k*((x-cx)*(x-cx)+(y-cy)*(y-cy)));
      return res;
    }

    float getRadialY(float x,float y,float cx,float cy,float k){
      x = (x*xscale+xshift);
      y = (y*yscale+yshift);
      float res = y+((y-cy)*k*((x-cx)*(x-cx)+(y-cy)*(y-cy)));
      return res;
    }

    float thresh = 1;
    float calc_shift(float x1,float x2,float cx,float k){
      float x3 = x1+(x2-x1)*0.5;
      float res1 = x1+((x1-cx)*k*((x1-cx)*(x1-cx)));
      float res3 = x3+((x3-cx)*k*((x3-cx)*(x3-cx)));

      //  std::cerr<<"x1: "<<x1<<" - "<<res1<<" x3: "<<x3<<" - "<<res3<<std::endl;

      if(res1>-thresh and res1 < thresh)
        return x1;
      if(res3<0){
        return calc_shift(x3,x2,cx,k);
      }
      else{
        return calc_shift(x1,x3,cx,k);
      }
    }

    int main(int argc, char** argv)
    {
      IplImage* src = cvLoadImage( argv[1], 1 );
      IplImage* dst = cvCreateImage(cvGetSize(src),src->depth,src->nChannels);
      IplImage* dst2 = cvCreateImage(cvGetSize(src),src->depth,src->nChannels);
      float K=atof(argv[3]);
      float centerX=atoi(argv[4]);
      float centerY=atoi(argv[5]);
      int width = cvGetSize(src).width;
      int height = cvGetSize(src).height;

      xshift = calc_shift(0,centerX-1,centerX,K);
      float newcenterX = width-centerX;
      float xshift_2 = calc_shift(0,newcenterX-1,newcenterX,K);

      yshift = calc_shift(0,centerY-1,centerY,K);
      float newcenterY = height-centerY;
      float yshift_2 = calc_shift(0,newcenterY-1,newcenterY,K);
      //  scale = (centerX-xshift)/centerX;
      xscale = (width-xshift-xshift_2)/width;
      yscale = (height-yshift-yshift_2)/height;

      std::cerr<<xshift<<" "<<yshift<<" "<<xscale<<" "<<yscale<<std::endl;
      std::cerr<<cvGetSize(src).height<<std::endl;
      std::cerr<<cvGetSize(src).width<<std::endl;

      for(int j=0;j<cvGetSize(dst).height;j++){
        for(int i=0;i<cvGetSize(dst).width;i++){
          CvScalar s;
          float x = getRadialX((float)i,(float)j,centerX,centerY,K);
          float y = getRadialY((float)i,(float)j,centerX,centerY,K);
          sampleImage(src,y,x,s);
          cvSet2D(dst,j,i,s);

        }
      }
    #if 0
      cvNamedWindow( "Source1", 1 );
      cvShowImage( "Source1", dst);
      cvWaitKey(0);
    #endif

      cvSaveImage(argv[2],dst,0);

    #if 0
      for(int j=0;j<cvGetSize(src).height;j++){
        for(int i=0;i<cvGetSize(src).width;i++){
          CvScalar s;
          sampleImage(src,j+0.25,i+0.25,s);
          cvSet2D(dst,j,i,s);
        }
      }

      cvNamedWindow( "Source1", 1 );
      cvShowImage( "Source1", src);
      cvWaitKey(0);

    #endif  

}

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