OpenCV实现给图片添加边框功能

目标：

基于OpenCV的函数cv::copyMakeBorder给图像添加边框

函数简介：

copyMakeBorder( src, dst, top, bottom, left, right, borderType, value );

参数:

src: 原图像
dst: 目标图像
top, bottom, left, right: 每一个边界方向上像素的宽度.在这里使用图像原始大小的 5% .
borderType:边框的类型 。当前例子中位纯色或者边界的复制.
value: 如果borderType 设置位 BORDER_CONSTANT, 这个将作为边框的颜色.

边框的类型

1）纯色边框

    BORDER_CONSTANT，边框设置位某种单一的颜色，比如黑色

2）图像边界扩展

BORDER_REPLICATE，复制原图的边界进行扩展

代码

/**
 * @file copyMakeBorder_demo.cpp
 * @brief Sample code that shows the functionality of copyMakeBorder
 * @author OpenCV team
 */
 
#include "opencv2/imgproc.hpp"
#include "opencv2/imgcodecs.hpp"
#include "opencv2/highgui.hpp"
 
using namespace cv;
 
//![variables]
Mat src, dst;
int top, bottom, left, right;
int borderType;
const char* window_name = "copyMakeBorder Demo";
RNG rng(12345);
//![variables]
 
/**
 * @function main
 */
int main( int, char** argv )
{
 
 int c;
 
 //![load]
 src = imread( argv[1], IMREAD_COLOR ); // Load an image
 
 if( src.empty() )
 {
  printf(" No data entered, please enter the path to an image file \n");
  return -1;
 }
 //![load]
 
 /// Brief how-to for this program
 printf( "\n \t copyMakeBorder Demo: \n" );
 printf( "\t -------------------- \n" );
 printf( " ** Press 'c' to set the border to a random constant value \n");
 printf( " ** Press 'r' to set the border to be replicated \n");
 printf( " ** Press 'ESC' to exit the program \n");
 
 //![create_window]
 namedWindow( window_name, WINDOW_AUTOSIZE );
 //![create_window]
 
 //![init_arguments]
 /// Initialize arguments for the filter
 top = (int) (0.05*src.rows); bottom = (int) (0.05*src.rows);
 left = (int) (0.05*src.cols); right = (int) (0.05*src.cols);
 //![init_arguments]
 
 dst = src;
 imshow( window_name, dst );
 
 for(;;)
  {
   //![check_keypress]
   c = waitKey(500);
 
   if( (char)c == 27 )
   { break; }
   else if( (char)c == 'c' )
   { borderType = BORDER_CONSTANT; }
   else if( (char)c == 'r' )
   { borderType = BORDER_REPLICATE; }
   //![check_keypress]
 
   //![update_value]
   Scalar value( rng.uniform(0, 255), rng.uniform(0, 255), rng.uniform(0, 255) );
   //![update_value]
 
   //![copymakeborder]
   copyMakeBorder( src, dst, top, bottom, left, right, borderType, value );
   //![copymakeborder]
 
   //![display]
   imshow( window_name, dst );
   //![display]
  }
 
 return 0;
}

效果

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