Question

我尝试优化this代码，特别是：

bool interpolate(const Mat &im, float ofsx, float ofsy, float a11, float a12, float a21, float a22, Mat &res)
{         
   bool ret = false;
   // input size (-1 for the safe bilinear interpolation)
   const int width = im.cols-1;
   const int height = im.rows-1;
   // output size
   const int halfWidth  = res.cols >> 1;
   const int halfHeight = res.rows >> 1;
   float *out = res.ptr<float>(0);
   for (int j=-halfHeight; j<=halfHeight; ++j)
   {
      const float rx = ofsx + j * a12;
      const float ry = ofsy + j * a22;
      for(int i=-halfWidth; i<=halfWidth; ++i)
      {
         float wx = rx + i * a11;
         float wy = ry + i * a21;
         const int x = (int) floor(wx);
         const int y = (int) floor(wy);
         if (x >= 0 && y >= 0 && x < width && y < height)
         {
            // compute weights
            wx -= x; wy -= y;
            // bilinear interpolation
            *out++ = 
               (1.0f - wy) * ((1.0f - wx) * im.at<float>(y,x)   + wx * im.at<float>(y,x+1)) +
               (       wy) * ((1.0f - wx) * im.at<float>(y+1,x) + wx * im.at<float>(y+1,x+1));
         } else {
            *out++ = 0;
            ret =  true; // touching boundary of the input            
         }
      }
   }
   return ret;
}

根据英特尔顾问的说法，这是一个非常耗时的功能。在this问题中，我问我如何优化这一点，someone让我注意到这是经线仿射变换。

现在，由于我不是图像处理人员，所以我必须阅读this文章才能了解经线仿真变换是什么。

根据我的理解，给定一个点p=(x,y)，您应用转换A（2x2矩阵），然后通过向量b进行转换。因此，转换后p'获得的点可以表示为p' = A*p+b。到现在为止还挺好。

但是，我对如何将cv::warpAffine()应用于此案件感到有些困惑。首先，从interpolate()上面的函数我只能看到4个A组件（a11，a12，a21，a22），虽然我看不到2个b组件......他们是ofsx还是ofy？

另外注意到这个函数返回一个bool值，warpAffine没有返回（这个布尔值在第126行使用here），所以我不知道＃39;我知道我可以使用OpenCV功能。

但最重要的是，我对for (int j=-halfHeight; j<=halfHeight; ++j)和for(int i=-halfWidth; i<=halfWidth; ++i)以及内部发生的所有垃圾感到困惑。

我理解：

        // bilinear interpolation
        *out++ = 
           (1.0f - wy) * ((1.0f - wx) * im.at<float>(y,x)   + wx * im.at<float>(y,x+1)) +
           (       wy) * ((1.0f - wx) * im.at<float>(y+1,x) + wx * im.at<float>(y+1,x+1));

是INTER_LINEAR的作用，但除此之外，我完全迷失了。

因此，为了测试我的方法，我尝试将this的第131行视为：

     bool touchesBoundary = interpolate(smoothed, (float)(patchImageSize>>1), (float)(patchImageSize>>1), imageToPatchScale, 0, 0, imageToPatchScale, patch);
     Mat warp_mat( 2, 3, CV_32FC1 );
     float a_11 = imageToPatchScale;
     float a_12 = 0;
     float a_21 = 0;
     float a_22 = imageToPatchScale;
     float ofx = (float)(patchImageSize>>1);
     float ofy = (float)(patchImageSize>>1);
     float ofx_new = ofx - a12*halfHeight - a11*halfWidth;
     float ofy_new = ofy - a22*halfHeight - a21*halfWidth;
     warp_mat.at<float>(0,0) = imageToPatchScale;
     warp_mat.at<float>(0,1) = 0;
     warp_mat.at<float>(0,2) = ofx_new;
     warp_mat.at<float>(1,0) = 0;
     warp_mat.at<float>(1,1) = imageToPatchScale;
     warp_mat.at<float>(1,2) = ofy_new;
     cv::Mat myPatch;
     std::cout<<"Applying warpAffine"<<std::endl;
     warpAffine(smoothed, myPatch, warp_mat, patch.size());
     std::cout<<"WarpAffineApplied patch size="<<patch.size()<<" myPatch size="<<myPatch.size()<<std::endl;
     cv::Mat diff = patch!=myPatch;
     if(cv::countNonZero(diff) != 0){
         throw std::runtime_error("Warp affine doesn't work!");
     }
     else{
         std::cout<<"It's working!"<<std::endl;
     }

当然，第一次执行此操作时，会抛出异常（因此这两种方法不相同）...我该如何解决这个问题？

有人能帮助我吗？

正如我在评论中所写，使用上面代码生成的矩阵是零矩阵。虽然使用maPatch和ofx代替ofy和ofx_new获得ofy_new，但patch的所有值都不同于零：

[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 229.78679, 229.5752, 229.11732, 229.09612, 229.84615, 230.28633, 230.35257, 230.70955, 230.99368, 231.00777, 231.20511, 231.63196, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 230.60367, 230.16417, 230.07034, 230.06793, 230.02016, 230.14925, 230.60413, 230.84822, 230.92368, 231.02249, 230.99162, 230.9149, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 232.76547, 231.39716, 231.26674, 231.34512, 230.746, 230.25253, 229.65276, 227.83998, 225.43642, 229.57695, 230.31363, 230.16011, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 234.01663, 232.88118, 232.15475, 231.40129, 223.21553, 208.22626, 205.58975, 214.53882, 220.32681, 228.11552, 229.31509, 228.86545, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 234.04565, 233.00443, 231.9902, 230.14912, 198.0849, 114.86175, 97.901344, 160.0218, 217.38528, 231.07045, 231.13109, 231.10185, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 233.293, 232.69095, 217.03873, 190.56714, 167.61592, 94.968391, 81.302032, 150.72263, 194.79535, 215.15564, 230.01717, 232.37894, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 231.70988, 227.81319, 207.59377, 173.35149, 113.88276, 73.171112, 71.523285, 103.05875, 160.05588, 194.65132, 226.4287, 231.45871, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 231.93924, 224.24269, 199.1693, 150.65695, 103.33984, 79.489555, 77.509094, 87.893059, 122.01918, 168.37506, 219.22086, 231.05161, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 232.2706, 232.12926, 206.97635, 127.69308, 92.714355, 81.512207, 74.89402, 75.968353, 84.518105, 157.07962, 223.18773, 229.92766, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 232.64882, 222.16704, 161.95021, 92.577881, 83.757164, 76.764214, 67.041054, 66.195595, 71.112335, 131.66878, 188.27278, 217.6635, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 234.77202, 231.75511, 178.64326, 104.27015, 95.664223, 82.791382, 67.68969, 72.78054, 72.355469, 104.77696, 172.32361, 204.92691, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 236.49684, 235.5802, 185.34337, 115.96995, 106.85963, 82.980408, 61.703068, 69.540627, 76.200562, 82.429321, 101.46993, 119.75877, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

Example of smoothed:

[229.78679, 229.67955, 229.56825, 229.40576, 229.08748, 228.90848, 229.13086, 229.53154, 229.91875, 230.1864, 230.31964, 230.34709, 230.35471, 230.51445, 230.81174, 230.97459, 231.00513, 231.00487, 231.01001, 231.08649, 231.30977, 231.55736, 231.71651;
 229.71237, 229.63612, 229.65092, 229.72298, 229.65163, 229.58559, 229.68594, 229.8093, 229.91052, 230.0466, 230.22325, 230.43683, 230.67668, 230.87794, 230.98672, 231.02505, 231.03383, 231.03091, 231.02097, 231.03201, 231.09761, 231.17659, 231.23175;
 230.66309, 230.37627, 230.1866, 230.1675, 230.09061, 230.03766, 230.10495, 230.09256, 230.01401, 230.03775, 230.18376, 230.42041, 230.67554, 230.82742, 230.84885, 230.87372, 230.94225, 231.01442, 231.02843, 231.00027, 230.97455, 230.9254, 230.86211;
 232.00514, 231.33768, 230.82791, 230.77686, 230.84599, 230.88741, 230.84238, 230.58279, 230.27737, 230.22282, 230.2531, 230.28053, 230.33743, 230.24406, 229.8969, 229.53674, 229.66661, 230.42201, 230.86761, 230.84827, 230.7677, 230.72296, 230.69333;
 232.84413, 232.07454, 231.4113, 231.24339, 231.31792, 231.42, 231.39203, 231.09439, 230.71797, 230.52229, 230.16359, 229.71872, 229.5307, 228.81219, 226.98767, 224.92525, 225.05101, 228.29745, 230.37059, 230.39821, 230.14323, 230.08817, 230.12051;
 233.69714, 233.27977, 232.63216, 231.97507, 231.61856, 231.50835, 231.37958, 230.94897, 230.22003, 229.17024, 227.78331, 226.92528, 227.3483, 226.49516, 223.07671, 219.54231, 220.02966, 225.84485, 229.56601, 229.69946, 229.2941, 228.91028, 228.47911;
 234.07579, 233.56334, 232.87689, 232.33269, 232.23909, 232.26355, 231.24196, 227.51971, 220.59465, 210.97746, 202.39467, 198.75334, 202.68945, 209.23911, 214.57399, 218.0966, 221.80714, 226.69366, 229.27985, 229.35699, 229.21922, 229.04704, 228.72176;
 234.02943, 233.1526, 232.62421, 232.68416, 232.63794, 232.74126, 230.84375, 220.47586, 197.81956, 164.03839, 136.08931, 125.05849, 134.9079, 158.19888, 186.67014, 209.67909, 223.89606, 229.51706, 230.72685, 230.50046, 230.31461, 230.29973, 230.30855;
 234.04939, 233.55843, 233.05295, 232.52957, 231.76837, 231.33992, 229.65753, 220.00912, 191.89427, 140.79909, 97.534477, 80.921623, 93.553299, 127.26912, 171.24872, 205.13603, 224.29935, 230.74513, 231.68158, 231.38503, 231.22385, 231.26157, 231.31372;
 233.67462, 233.69278, 233.09642, 230.73448, 225.79077, 220.33292, 216.52835, 212.6403, 192.7964, 142.2917, 93.74559, 73.776016, 92.972778, 136.18417, 183.40891, 209.98003, 220.25392, 225.67984, 229.14565, 230.97379, 231.68997, 231.87923, 231.80464;
 233.16579, 232.95818, 232.5157, 227.84683, 212.53104, 193.47, 179.53844, 171.00941, 154.97589, 118.29485, 82.342369, 67.311531, 83.867973, 119.85723, 158.53325, 180.67912, 191.74194, 203.44008, 216.87592, 227.59789, 231.31285, 232.24002, 232.91658;
 232.21611, 231.93192, 231.80423, 227.06053, 208.82571, 183.86725, 160.27481, 136.63663, 112.56454, 89.978371, 73.328209, 66.652176, 73.406273, 90.259987, 113.70027, 138.08961, 159.2791, 178.08627, 201.78604, 223.79007, 230.86775, 231.59146, 232.17819;
 231.5118, 230.38042, 225.97289, 217.07312, 205.34308, 192.29631, 174.19812, 142.59843, 105.71719, 80.45845, 68.488274, 67.021088, 73.29406, 86.493896, 110.19484, 145.04185, 174.52554, 187.26851, 202.64322, 221.51042, 229.94238, 231.48595, 231.08746;
 231.67564, 229.07423, 217.57478, 197.87076, 181.8385, 167.48799, 148.19232, 124.3977, 100.57513, 83.081154, 73.410683, 71.723045, 77.010704, 85.107651, 98.029099, 121.88382, 145.77963, 161.43314, 184.43152, 212.01347, 227.27411, 231.84755, 231.33319;
 232.0773, 231.27109, 227.09813, 218.50165, 206.31781, 182.26494, 144.46196, 115.64604, 99.402679, 87.584351, 79.348366, 76.547188, 79.332504, 82.244148, 86.3069, 100.71764, 122.39668, 147.5081, 179.02258, 210.10269, 226.37909, 231.12947, 230.34335;
 232.11732, 231.67418, 231.89207, 229.20001, 213.83904, 180.2238, 134.82561, 107.20949, 97.260231, 88.765694, 80.533333, 75.941055, 76.372505, 77.851997, 78.464508, 81.875244, 96.896721, 131.28108, 175.47084, 213.05406, 227.81297, 230.31032, 229.60373;
 232.36255, 232.00981, 232.29773, 226.30051, 199.48029, 156.13557, 112.30969, 91.346344, 88.295509, 85.21006, 79.416222, 74.552238, 73.894844, 75.069275, 74.349594, 72.166176, 85.453522, 128.47208, 180.33452, 218.87312, 229.58446, 229.77406, 230.03587;
 232.52425, 231.2455, 226.65468, 210.90804, 174.35748, 128.79022, 92.861343, 79.050415, 78.796555, 76.526512, 71.317635, 67.324234, 67.506172, 69.193619, 68.941025, 67.913399, 82.488945, 124.88449, 171.48178, 203.84958, 215.13747, 221.22523, 228.15715;
 232.74571, 229.80283, 217.69687, 189.34862, 145.52664, 104.71513, 84.893997, 83.699814, 88.473457, 86.446617, 77.834595, 68.74688, 65.925613, 65.426163, 63.241882, 61.236107, 69.682426, 97.213646, 131.60564, 160.99944, 180.75278, 202.22523, 223.85883;
 233.80923, 232.82767, 227.83594, 209.05493, 166.58002, 120.64989, 94.880188, 89.971268, 93.209671, 90.605591, 80.354561, 69.243584, 67.490875, 70.700516, 72.353569, 70.053764, 70.773293, 86.577957, 121.76624, 160.51776, 182.91074, 203.17424, 224.06786;
 235.62155, 235.22169, 234.91901, 223.3783, 181.88362, 132.80327, 104.59508, 97.904762, 98.472153, 91.749123, 79.65731, 69.025223, 66.806007, 70.64135, 75.239159, 74.961838, 73.406227, 83.469612, 118.84832, 161.62743, 181.61127, 192.7933, 203.54196;
 236.851, 236.1096, 235.65253, 224.02559, 182.0352, 134.56085, 111.10134, 106.82736, 105.87054, 95.272148, 80.614365, 68.017456, 61.20583, 62.735069, 69.976379, 72.687195, 71.943336, 75.369637, 89.042145, 106.32064, 116.6455, 127.58019, 139.77493;
 236.09546, 235.84727, 235.44041, 223.06668, 180.65508, 134.57915, 114.13975, 110.49339, 107.15049, 93.355858, 77.559898, 65.277794, 58.067509, 62.642029, 76.700447, 81.800919, 80.054298, 80.085251, 82.980927, 87.177017, 92.031647, 100.26192, 109.12404]

Answer 1

我更熟悉this warpAffine，其基本陈述是

cv::warpAffine (InputArray src,     // input mat
                OutputArray dst,    // output mat
                InputArray M,       // affine transformation mat
                Size dsize)         // size of the output mat

其中M是矩阵

      a11 a12 ofx
      a21 a22 ofy

在您的术语中，前两列是线性变换矩阵A，最后一列是平移向量b。

cv::hal::warpAffine()是相同的，其中double M[6]对应于上面的仿射变换矩阵，但我不确定它被压扁的顺序（最有可能是[a11,a12,ofx,a21,a22,ofy]）

在OpenCV中，原点(0,0)像往常一样左上角，而在英特尔代码中，原点(0,0)位于图像的中间。这就是部分

for (int j=-halfHeight; j<=halfHeight; ++j)
{
   for(int i=-halfWidth; i<=halfWidth; ++i)
      {
         const int y = (int) floor(wy);
         //...
   }
}

确实：(i,j)是res，j from -halfHeight to halfHeight和i from -halfHeight to halfHeight中的坐标。因此，在这种情况下，(0,0)位于res图片的中心。

在提供的代码中，如果您想将src映射到res（我猜），您需要执行以下操作：

    bool touchesBoundary = interpolate(smoothed, (float)(imageSize>>1), (float)(imageSize>>1), imageToPatchScale, 0, 0, imageToPatchScale, patch);

请注意imageSize>>1而不是patchImageSize>>1。为什么？您希望res（i=0,j=0）地图的中心位于src的中心，即值src.at<float>(src.cols/2, src.rows/2)（为什么？）

现在，为了在您的示例中完成这项工作，相当于cv::warpedAffine()将是

warpAffine(smoothed, myPatch, warp_mat, patch.size(),WARP_INVERSE_MAP);

warp_mat有ofsx=0,ofsy=0。

最后，这里是我尝试过的例子：

其中diff = mypatch - patch >5和smoothed由OS扩展。请注意patch中的黑色边框，这是因为代码中的限制为x < width和y<height。

如何使用OpenCV重写此warp-affine？

1 个答案: