c++ - 索贝尔中的opencv convertScaleAbs

Question

我在 OPENCV3.1.0 中进行 Sobel 计算。我不明白为什么它应该在这里做'convertScaleAbs'。

以下是主要代码：

#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/imgcodecs.hpp"
#include "opencv2/highgui/highgui.hpp"
#include <stdlib.h>
#include <stdio.h> 
using namespace cv;
int main( int, char** argv )
{
  Mat src, src_gray;
  Mat grad;
  const char* window_name = "Sobel Demo - Simple Edge Detector";
  int scale = 1;
  int delta = 0;
  int ddepth = CV_16S;
  src = imread( argv[1] );
  if( src.empty() )
    { return -1; }
  GaussianBlur( src, src, Size(3,3), 0, 0, BORDER_DEFAULT );
  cvtColor( src, src_gray, COLOR_RGB2GRAY );
  namedWindow( window_name, WINDOW_AUTOSIZE );
  Mat grad_x, grad_y;
  Mat abs_grad_x, abs_grad_y;
  //Scharr( src_gray, grad_x, ddepth, 1, 0, scale, delta, BORDER_DEFAULT );
  Sobel( src_gray, grad_x, ddepth, 1, 0, 3, scale, delta, BORDER_DEFAULT );
  convertScaleAbs( grad_x, abs_grad_x );
  //Scharr( src_gray, grad_y, ddepth, 0, 1, scale, delta, BORDER_DEFAULT );
  Sobel( src_gray, grad_y, ddepth, 0, 1, 3, scale, delta, BORDER_DEFAULT );
  convertScaleAbs( grad_y, abs_grad_y );
  addWeighted( abs_grad_x, 0.5, abs_grad_y, 0.5, 0, grad );
  imshow( window_name, grad );
  waitKey(0);
  return 0;
}

谁能帮忙解释一下？谢谢！