//Filters.h

#ifndef FILTERS_H
#define FILTERS_H#include "opencv2/imgproc.hpp"
#include "opencv2/highgui.hpp"
#include "opencv2/core.hpp"#include <iostream>
#include <cmath>//Bilateral Filtering
//sigmaD == sigmaSpace, sigmaR == sigmaColor
cv::Mat BilateralFilter(cv::Mat inputImg, int filterSize, double sigmaD, double sigmaR);cv::Mat fastBilateralFilter(cv::Mat inputImg, int filterSize, double sigmaD, double sigmaR);#endif // ! FILTERS_H

//Filters.cpp

#include "Filters.h"double SpaceFactor(int x1, int y1, int x2, int y2, double sigmaD) {double absX = pow(abs(x1 - x2), 2);double absY = pow(abs(y1 - y2), 2);return exp(-(absX + absY) / (2 * pow(sigmaD, 2)));
}double ColorFactor(int x, int y, double sigmaR) {double distance = abs(x - y) / sigmaR;return exp(-0.5 * pow(distance, 2));
}cv::Mat BilateralFilter(cv::Mat inputImg, int filterSize, double sigmaD, double sigmaR) {int len; //must be odd numbercv::Mat gray; // must be 1-channel imagecv::Mat LabImage; // if channels == 3if (filterSize % 2 != 1 || filterSize <= 0) {std::cerr << "Filter Size must be a positive odd number!" << std::endl;return inputImg;}len = filterSize / 2;if (inputImg.channels() >= 3) {cv::cvtColor(inputImg, LabImage, cv::COLOR_BGR2Lab);gray = cv::Mat::zeros(LabImage.size(), CV_8UC1);for (int i = 0; i < LabImage.rows; i++) {for (int j = 0; j < LabImage.cols; j++) {gray.ptr<uchar>(i)[j] = LabImage.ptr<uchar>(i, j)[0];}}}else if(inputImg.channels() == 1){inputImg.copyTo(gray);}else {std::cerr << "the count of input image's channel can not be 2!" << std::endl;return inputImg;}cv::Mat resultGrayImg = cv::Mat::zeros(gray.size(), CV_8UC1);for (int i = 0; i < gray.rows; i++) {for (int j = 0; j < gray.cols; j++) {double k = 0;double f = 0;for (int r = i - len; r <= i + len; r++) {for (int c = j - len; c <= j + len; c++) {if (r < 0 || c < 0 || r >= gray.rows || c >= gray.cols)continue;f = f + gray.ptr<uchar>(r)[c] * SpaceFactor(i, j, r, c, sigmaD) * ColorFactor(gray.ptr<uchar>(i)[j], gray.ptr<uchar>(r)[c], sigmaD);k += SpaceFactor(i, j, r, c, sigmaD) * ColorFactor(gray.ptr<uchar>(i)[j], gray.ptr<uchar>(r)[c], sigmaD);}}int value = f / k;if (value < 0) value = 0;else if (value > 255) value = 255;resultGrayImg.ptr<uchar>(i)[j] = (uchar)value;}}cv::Mat resultImg;if (inputImg.channels() >= 3) {for (int i = 0; i < LabImage.rows; i++) {for (int j = 0; j < LabImage.cols; j++) {LabImage.ptr<uchar>(i, j)[0] = resultGrayImg.ptr<uchar>(i)[j];}}cv::cvtColor(LabImage, resultImg, cv::COLOR_Lab2BGR);}else {resultGrayImg.copyTo(resultImg);}return resultImg;
}cv::Mat fastBilateralFilter(cv::Mat inputImg, int filterSize, double sigmaD, double sigmaR) {int len; //must be odd numbercv::Mat gray; // must be 1-channel imagecv::Mat LabImage; // if channels == 3if (filterSize % 2 != 1 || filterSize <= 0) {std::cerr << "Filter Size must be a positive odd number!" << std::endl;return inputImg;}len = filterSize / 2;if (inputImg.channels() >= 3) {cv::cvtColor(inputImg, LabImage, cv::COLOR_BGR2Lab);gray = cv::Mat::zeros(LabImage.size(), CV_8UC1);for (int i = 0; i < LabImage.rows; i++) {for (int j = 0; j < LabImage.cols; j++) {gray.ptr<uchar>(i)[j] = LabImage.ptr<uchar>(i, j)[0];}}}else if (inputImg.channels() == 1) {inputImg.copyTo(gray);}else {std::cerr << "the count of input image's channel can not be 2!" << std::endl;return inputImg;}cv::Mat resultGrayImg = cv::Mat::zeros(gray.size(), CV_8UC1);for (int i = 0; i < gray.rows; i++) {for (int j = 0; j < gray.cols; j++) {double k = 0;double f = 0;double sum = 0;for (int r = i - len; r <= i + len; r++) {if (r < 0 || r >= gray.rows)continue;f = f + gray.ptr<uchar>(r)[j] * SpaceFactor(i, j, r, j, sigmaD) * ColorFactor(gray.ptr<uchar>(i)[j], gray.ptr<uchar>(r)[j], sigmaD);k += SpaceFactor(i, j, r, j, sigmaD) * ColorFactor(gray.ptr<uchar>(i)[j], gray.ptr<uchar>(r)[j], sigmaD);}sum = f / k;f = k = 0.0;for (int c = j - len; c <= j + len; c++) {if (c < 0 || c >= gray.cols)continue;f = f + gray.ptr<uchar>(i)[c] * SpaceFactor(i, j, i, c, sigmaD) * ColorFactor(gray.ptr<uchar>(i)[j], gray.ptr<uchar>(i)[c], sigmaD);k += SpaceFactor(i, j, i, c, sigmaD) * ColorFactor(gray.ptr<uchar>(i)[j], gray.ptr<uchar>(i)[c], sigmaD);}int value = (sum + f / k) / 2;if (value < 0) value = 0;else if (value > 255) value = 255;resultGrayImg.ptr<uchar>(i)[j] = (uchar)value;}}cv::Mat resultImg;if (inputImg.channels() >= 3) {for (int i = 0; i < LabImage.rows; i++) {for (int j = 0; j < LabImage.cols; j++) {LabImage.ptr<uchar>(i, j)[0] = resultGrayImg.ptr<uchar>(i)[j];}}cv::cvtColor(LabImage, resultImg, cv::COLOR_Lab2BGR);}else {resultGrayImg.copyTo(resultImg);}return resultImg;
}

//main.cpp

#include <iostream>
#include <time.h>#include "Filters.h"using namespace std;int main() {cv::Mat img = cv::imread("Capture.jpg", cv::IMREAD_UNCHANGED);clock_t begin_time = clock();cv::Mat result = BilateralFilter(img, 15, 12.5, 50);std::cout << float(clock() - begin_time) / CLOCKS_PER_SEC << std:: endl;cv::imshow("original", result);cv::waitKey(0);cv::imwrite("original.jpg", result);begin_time = clock();result = fastBilateralFilter(img, 15, 12.5, 50);std::cout << float(clock() - begin_time) / CLOCKS_PER_SEC << std::endl;cv::imshow("fast", result);cv::waitKey(0);cv::imwrite("fast.jpg", result);begin_time = clock();cv::bilateralFilter(img, result, 15, 50, 12.5);std::cout << float(clock() - begin_time) / CLOCKS_PER_SEC << std::endl;cv::imshow("opencv", result);cv::waitKey(0);cv::imwrite("opencv.jpg", result);system("pause");return 0;
}