[copyMakeBorder]添加边界¶
参考:Adding borders to your images
OpenCV
提供函数copyMakeBorder()来添加图像边界
声明¶
头文件声明:#include <opencv2/core.hpp>
解析¶
CV_EXPORTS_W void copyMakeBorder(InputArray src, OutputArray dst,
int top, int bottom, int left, int right,
int borderType, const Scalar& value = Scalar() );
src
:原图dst
:结果图像,其大小为Size(src.cols+left+right, src.rows+top+bottom)
top
:指定图像上方填充多少像素。其他方向同理bottom
left
right
borderType
:填充类型value:borderType==BORDER_CONSTANT
的填充值。默认值为0
的Scalar
函数将源图像复制到目标图像的中间。在源图像左侧、右侧、上方和下方的区域进行像素填充
填充类型¶
borderType == BORDER_CONSTRAINT
:指定像素值进行填充borderType== BORDER_REPLICATE
:使用边缘像素值进行填充
示例¶
#include "opencv2/imgproc.hpp"
#include "opencv2/imgcodecs.hpp"
#include "opencv2/highgui.hpp"
using namespace cv;
// Declare the variables
Mat src, dst;
int top, bottom, left, right;
int borderType = BORDER_CONSTANT;
const char *window_name = "copyMakeBorder Demo";
RNG rng(12345);
int main(int argc, char **argv) {
const char *imageName = argc >= 2 ? argv[1] : "../lena.jpg";
// Loads an image
src = imread(imageName, IMREAD_COLOR); // Load an image
// Check if image is loaded fine
if (src.empty()) {
printf(" Error opening image\n");
printf(" Program Arguments: [image_name -- default ../data/lena.jpg] \n");
return -1;
}
// 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");
namedWindow(window_name, WINDOW_AUTOSIZE);
// Initialize arguments for the filter
top = (int) (0.05 * src.rows);
bottom = top;
left = (int) (0.05 * src.cols);
right = left;
for (;;) {
Scalar value(rng.uniform(0, 255), rng.uniform(0, 255), rng.uniform(0, 255));
copyMakeBorder(src, dst, top, bottom, left, right, borderType, value);
imshow(window_name, dst);
char c = (char) waitKey(500);
if (c == 27) { break; }
else if (c == 'c') { borderType = BORDER_CONSTANT; }
else if (c == 'r') { borderType = BORDER_REPLICATE; }
}
return 0;
}
设置为BORDER_CONSTRAINT
时
设置为BORDER_REPLICATE
时