C＃Opencv 3.0 Ovelay Alpha图像

Question

我正在尝试使用此https://github.com/shimat/opencvsharp

将C ++代码移植到C＃中

这是C ++代码：

void Ball::overlayImage(const cv::Mat &background, const cv::Mat &foreground, 
  cv::Mat &output, cv::Point2i location)
{
  background.copyTo(output);

  // start at the row indicated by location, or at row 0 if location.y is negative.
  for(int y = std::max(location.y , 0); y < background.rows; ++y)
  {
    int fY = y - location.y; // because of the translation

    // we are done of we have processed all rows of the foreground image.
    if(fY >= foreground.rows)
      break;

    // start at the column indicated by location, 

    // or at column 0 if location.x is negative.
    for(int x = std::max(location.x, 0); x < background.cols; ++x)
    {
      int fX = x - location.x; // because of the translation.

      // we are done with this row if the column is outside of the foreground image.
      if(fX >= foreground.cols)
        break;

      // determine the opacity of the foregrond pixel, using its fourth (alpha) channel.
      double opacity =
        ((double)foreground.data[fY * foreground.step + fX * foreground.channels() + 3])/ 255.;


      // and now combine the background and foreground pixel, using the opacity, 

      // but only if opacity > 0.
      for(int c = 0; opacity > 0 && c < output.channels(); ++c)
      {
        unsigned char foregroundPx =
          foreground.data[fY * foreground.step + fX * foreground.channels() + c];
        unsigned char backgroundPx =
          background.data[y * background.step + x * background.channels() + c];
        output.data[y*output.step + output.channels()*x + c] =
          backgroundPx * (1.-opacity) + foregroundPx * opacity;


      }

    }
  }
}

这是我移植的代码

public void overlayImage(ref Mat background, ref Mat foreground, ref Mat output, Point location)
        {
            background.CopyTo(output);

            // start at the row indicated by location, or at row 0 if location.y is negative.
            for (int y = Math.Max(location.Y, 0); y < background.Rows; ++y)
            {
                int fY = y - location.Y; // because of the translation

                // we are done of we have processed all rows of the foreground image.
                if (fY >= foreground.Rows)
                    break;

                // start at the column indicated by location, 

                // or at column 0 if location.x is negative.
                for (int x = Math.Max(location.X, 0); x < background.Cols; ++x)
                {
                    int fX = x - location.X; // because of the translation.

                    // we are done with this row if the column is outside of the foreground image.
                    if (fX >= foreground.Cols)
                        break;

                    // determine the opacity of the foregrond pixel, using its fourth (alpha) channel.
                    double opacity =
                      ((double)foreground.data[fY * foreground.step + fX * foreground.channels() + 3])/ 255.;


                    // and now combine the background and foreground pixel, using the opacity, 

                    // but only if opacity > 0.
                    for (int c = 0; opacity > 0 && c < output.channels(); ++c)
                    {
                        unsigned char foregroundPx =
                          foreground.data[fY * foreground.step + fX * foreground.channels() + c];
                        unsigned char backgroundPx =
                          background.data[y * background.step + x * background.channels() + c];
                        output.data[y * output.step + output.channels() * x + c] =
                          backgroundPx * (1.- opacity) + foregroundPx * opacity;
                    }

                }
            }
        }

函数overlay基本上是尝试在指定Point（x，y）的背景图像上覆盖png图像（包含alpha图像）。 C ++函数完美地工作，它最初是用opencv 2.4 C ++编码的。端口不完整，这些行越来越错误。 double opacity =（（double）foreground.data [fY * front.step + fX * front.channels（）+ 3]）/ 255.0;

无符号字符前景Px =                           前景数据[fY *前景步骤+ fX *前景通道（）+ c];