图像的padding操作

为了完成卷积后图像大小不变，原始图像需要进行边界填充

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

bordertype:

BORDER_DEFAULT  填充黑色

BORDER_CONSTANT  用指定像素填充边界

BORDER_REPLICATE  用一只边缘像素填充边缘像素

BORDER_WARP  用另一边像素来补偿填充

#include"pch.h"
#include<iostream>
#include<opencv2/opencv.hpp>

using namespace std;
using namespace cv;

int main(int argc, char**argv)
{
    Mat src, dst;
    src = imread("b.jpg");
    if (src.empty())
    {
        cout << "Load img failed" << endl;
        return -1;
    }
    imshow("input img", src);

    int top = (int)(src.rows*0.05);
    int bottom = (int)(src.rows*0.05);
    int left = (int)(src.cols*0.05);
    int right = (int)(src.cols*0.05);

    RNG rng(12345);
    int borderType = BORDER_DEFAULT;
    int c = 0;

    while (true)
    {
        c = waitKey(500);
        if ((char)c == 27)//esc
        {
            break;
        }
        if ((char)c == 'r')
        {
            borderType = BORDER_REPLICATE;
        }
        else if ((char)c == 'w')
        {
            borderType = BORDER_WRAP;
        }
        else if ((char)c == 'c')
        {
            borderType = BORDER_CONSTANT;
        }
        else
        {
            borderType = BORDER_DEFAULT;
        }
        Scalar color = Scalar(rng.uniform(0, 255), rng.uniform(0, 255), rng.uniform(0, 255));
        copyMakeBorder(src, dst, top, bottom, left, right, borderType, color);
        imshow("output", dst);
    }
    waitKey(0);
    return 0;
}