OpenCV——LBP(Local Binary Patterns)特征检测

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

 using namespace cv;
 using namespace std;

 Mat src, gray_src;

 const char* output_tt = "LBP Result";

 int main(int argc, char** argv) {
     src = imread("test.jpg");
     if (src.empty()) {
         printf("could not load image...\n");
         return -;
     }

     namedWindow("input image", CV_WINDOW_AUTOSIZE);
     namedWindow(output_tt, CV_WINDOW_AUTOSIZE);
     imshow("input image", src);

     // convert to gray
     cvtColor(src, gray_src, COLOR_BGR2GRAY);
     int width = gray_src.cols;
     int height = gray_src.rows;

     // 基本LBP演示
     Mat lbpImage = Mat::zeros(gray_src.rows - , gray_src.cols - , CV_8UC1);//3*3窗口，边界有左右各1个像素不处理
     for (int row = ; row < height - ; row++) {
         for (int col = ; col < width - ; col++) {
             uchar c = gray_src.at<uchar>(row, col);//获取中心像素值
             uchar code = ;//特征码
             code |= (gray_src.at<uchar>(row - , col - ) > c) << ;
             code |= (gray_src.at<uchar>(row - , col) > c) << ;
             code |= (gray_src.at<uchar>(row - , col + ) > c) << ;
             code |= (gray_src.at<uchar>(row, col + ) > c) << ;
             code |= (gray_src.at<uchar>(row + , col + ) > c) << ;
             code |= (gray_src.at<uchar>(row + , col) > c) << ;
             code |= (gray_src.at<uchar>(row + , col - ) > c) << ;
             code |= (gray_src.at<uchar>(row, col - ) > c) << ;
             lbpImage.at<uchar>(row - , col - ) = code;//原图1，1=效果图0，0
         }
     }
     imshow(output_tt, lbpImage);

     waitKey();
     return ;
 }

LBP的扩展（多尺度表达）：

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

 using namespace cv;
 using namespace std;

 Mat src, gray_src;
 int current_radius = ;
 int max_count = ;

 const char* output_tt = "LBP Result";

 void ELBP_Demo(int, void*);
 int main(int argc, char** argv) {
     src = imread("test.jpg");
     if (src.empty()) {
         printf("could not load image...\n");
         return -;
     }

     namedWindow("input image", CV_WINDOW_AUTOSIZE);
     namedWindow(output_tt, CV_WINDOW_AUTOSIZE);
     imshow("input image", src);

     // convert to gray
     cvtColor(src, gray_src, COLOR_BGR2GRAY);
     int width = gray_src.cols;
     int height = gray_src.rows;

     // 基本LBP演示
     Mat lbpImage = Mat::zeros(gray_src.rows - , gray_src.cols - , CV_8UC1);//3*3窗口，边界有左右各1个像素不处理
     for (int row = ; row < height - ; row++) {
         for (int col = ; col < width - ; col++) {
             uchar c = gray_src.at<uchar>(row, col);//获取中心像素值
             uchar code = ;//特征码
             code |= (gray_src.at<uchar>(row - , col - ) > c) << ;
             code |= (gray_src.at<uchar>(row - , col) > c) << ;
             code |= (gray_src.at<uchar>(row - , col + ) > c) << ;
             code |= (gray_src.at<uchar>(row, col + ) > c) << ;
             code |= (gray_src.at<uchar>(row + , col + ) > c) << ;
             code |= (gray_src.at<uchar>(row + , col) > c) << ;
             code |= (gray_src.at<uchar>(row + , col - ) > c) << ;
             code |= (gray_src.at<uchar>(row, col - ) > c) << ;
             lbpImage.at<uchar>(row - , col - ) = code;
         }
     }
     imshow(output_tt, lbpImage);

     // ELBP 演示

     namedWindow("ELBP Result", CV_WINDOW_AUTOSIZE);
     createTrackbar("ELBP Radius:", "ELBP Result", &current_radius, max_count, ELBP_Demo);
     ELBP_Demo(, );

     waitKey();
     return ;
 }

 void ELBP_Demo(int, void*) {
     int offset = current_radius * ;//输出图无法计算到的边界宽度
     Mat elbpImage = Mat::zeros(gray_src.rows - offset, gray_src.cols - offset, CV_8UC1);
     int width = gray_src.cols;
     int height = gray_src.rows;

     int numNeighbors = ;//应根据半径变化，为了简便这里固定为8
     for (int n = ; n < numNeighbors; n++) {
         float x = static_cast<float>(current_radius) * cos(2.0 * CV_PI*n / static_cast<float>(numNeighbors));//x=r*cos(2*PI*n/8)
         float y = static_cast<float>(current_radius) * -sin(2.0 * CV_PI*n / static_cast<float>(numNeighbors));

         int fx = static_cast<int>(floor(x));//floor“向下取整”
         int fy = static_cast<int>(floor(y));
         int cx = static_cast<int>(ceil(x));//ceil“向上取整”
         int cy = static_cast<int>(ceil(y));

         //双线性插值
         float ty = y - fy;
         float tx = x - fx;

         //双线性插值，周边4个点的权重
         float w1 = ( - tx)*( - ty);
         float w2 = tx * ( - ty);
         float w3 = ( - tx)* ty;
         float w4 = tx * ty;

         for (int row = current_radius; row < (height - current_radius); row++) {
             for (int col = current_radius; col < (width - current_radius); col++) {
                 float t = w1 * gray_src.at<uchar>(row + fy, col + fx) + w2 * gray_src.at<uchar>(row + fy, col + cx) +
                     w3 * gray_src.at<uchar>(row + cy, col + fx) + w4 * gray_src.at<uchar>(row + cy, col + cx);
                 elbpImage.at<uchar>(row - current_radius, col - current_radius) +=
                     ((t > gray_src.at<uchar>(row, col)) && (abs(t - gray_src.at<uchar>(row, col)) > std::numeric_limits<float>::epsilon())) << n;
             }
         }
     }
     imshow("ELBP Result", elbpImage);
     return;
 }