#include <opencv2/opencv.hpp> 
using namespace cv;  
using namespace std; 
#define RATIO 0.25
#define WEIGHT 2
#define DELTA 20
#define  ALPHA 0.15
#define  BETA 0.85

int _tmain(int argc, _TCHAR* argv[])
{
  // 准备源图像
  IplImage* src = cvLoadImage("..\\image.jpg");
  int width = src->width;
  int height = src->height;

  //cvSetImageROI(src, cvRect(0, (1-RATIO)*height, width, height));
  int mir_w = width;
  int mir_h = RATIO*height;
  IplImage* mir = cvCreateImage(cvSize(width, RATIO*height) ,src->depth, src->nChannels);
  //cvCopy(src, mir);// 拷贝有bug
  //cvResetImageROI(src);
  // 从源图像拷贝1/4图像作为镜像图像
  for (int i=0; i<width; i++)
  {
    for (int j=(1-RATIO)*height; j<height; j++)
    {
      uchar* pSrc = &CV_IMAGE_ELEM(src, uchar, j, i*3);
      uchar* pDst = &CV_IMAGE_ELEM(mir, uchar, (int)(j-(1-RATIO)*height), i*3);
      pDst[0] = pSrc[0];  //B
      pDst[1] = pSrc[1];  //G
      pDst[2] = pSrc[2];  //R
    }
  }
  cvFlip(mir, NULL, 0);// 0：上下镜像；1：左右镜像

  // 准备最终结果图像
  CvSize dstSize;
  dstSize.width = width;
  dstSize.height = height + mir_h;
  IplImage* dst = cvCreateImage(dstSize, src->depth, src->nChannels);
  cvZero(dst);

  // 载入源图像到结果图像中
  cvSetImageROI(dst, cvRect(0, 0, width, height));
  cvCopy(src, dst);
  cvResetImageROI(dst);

  // 准备镜像图像
  IplImage* mask = cvCreateImage(cvSize(mir_w, mir_h), mir->depth, mir->nChannels);
  CvScalar a = CV_RGB(255, 255, 255);
  CvScalar b = CV_RGB(0, 0, 0);
  cvSet(mask, a);

  CvPoint origin = cvPoint(mir_w/2, 0);       // 光源设在镜像图像上方
  //CvPoint center = cvPoint(mir_w/2, mir_h/2);

  float distance = (mir_w-1 - origin.x)*
    (mir_w-1 - origin.x)+             // 光源与图像右下角的距离
    (mir_h-1 - origin.y)*
    (mir_h-1 - origin.y);
  distance = sqrt(distance);

  //double weightB = (b.val[0] - a.val[0])/distance;  // 分别计算BGR三个通道的权重
  //double weightG = (b.val[1] - a.val[1])/distance;
  //double weightR = (b.val[2] - a.val[2])/distance;
  double weight = (b.val[0] - a.val[0])/distance; // 计算BGR三个通道的权重 -1.72

  for ( int i=0; i<mask->width; i++)
  {
    for (int j=0; j<mask->height; j++)
    {
      float dist = WEIGHT*(j-origin.y)*(j-origin.y);
      dist = sqrt(dist);
      uchar* ptr = &CV_IMAGE_ELEM(mask, uchar, j, i*3);
      ptr[0] = cvRound(ptr[0] + weight*dist-DELTA); //B
      ptr[1] = cvRound(ptr[1] + weight*dist-DELTA); //G
      ptr[2] = cvRound(ptr[2] + weight*dist-DELTA); //R
    }
  }
  cvAddWeighted(mir,ALPHA , mask, BETA, 0, mir);

  // 载入镜像图像到结果图像中
  cvSetImageROI(dst, cvRect(0, height, mir_w, mir_h));
  cvCopy(mir, dst);
  cvResetImageROI(dst);

  cvNamedWindow( "test", 1);
  cvShowImage( "test", dst);
  cvWaitKey();

  // 释放资源
  cvDestroyWindow("test");
  cvReleaseImage(&src);
  cvReleaseImage(&dst);
  cvReleaseImage(&mask);
  cvReleaseImage(&mir);
  return 0;
}

运行结果如下：

opencv 实现图像倒影（渐变）效果【源码】_i++

参考：

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