图像的二阶导数
在二阶导数的时候，最大变化处的值为零即边缘是零值。通过二阶
导数计算，依据此理论我们可以计算图像二阶导数，提取边缘。
Laplance算子
void Laplacian( InputArray src, OutputArray dst, int ddepth,int ksize = 1, double scale = 1, double delta = 0,int borderType = BORDER_DEFAULT );
代码示例
#include <opencv2/opencv.hpp>
#include <iostream>using namespace cv;
int main(int argc, char** argv) {Mat src, dst;src = imread("D:/vcprojects/images/lena.png");if (!src.data) {printf("could not load image");}char input_title[] = "input image";char output_title[] = "Laplaiance Result";namedWindow(input_title);imshow(input_title, src);Mat gray_src, edge_image;GaussianBlur(src, dst, Size(3, 3), 0, 0);cvtColor(dst, gray_src, COLOR_BGR2GRAY);Laplacian(gray_src, edge_image, CV_16S, 3);convertScaleAbs(edge_image, edge_image);threshold(edge_image, edge_image, 0, 255, THRESH_OTSU | THRESH_BINARY);namedWindow(output_title, CV_WINDOW_AUTOSIZE);imshow(output_title, edge_image);waitKey(0);return 0;
}
