Add sample code for response calibration.

Author: nynyg

modules/photometric_calib/samples/response_calibration.cpp

@@ -0,0 +1,56 @@
+#include <string>
+#include <iostream>
+#include <iomanip>
+#include <vector>
+
+#include "opencv2/opencv.hpp"
+#include "opencv2/core.hpp"
+#include "opencv2/highgui.hpp"
+#include "opencv2/photometric_calib.hpp"
+#include "opencv2/imgproc/imgproc.hpp"
+
+using namespace std;
+using namespace cv;
+
+int main(int argc, char **argv)
+{
+    // Please down load the sample dataset from:
+    // https://www.dropbox.com/s/5x48uhc7k2bgjcj/GSoC2017_PhotometricCalib_Sample_Data.zip?dl=0
+    // By unzipping the file, you would get a folder named /GSoC2017_PhotometricCalib_Sample_Data which contains 4 subfolders:
+    // response_calib, response remover, vignette_calib, vignette_remover
+    // in this sample, we will use the data in the folder response_calib and response_remover
+
+    // Prefix for the data, e.g. /Users/Yelen/GSoC2017_PhotometricCalib_Sample
+    string userPrefix = "/Users/Yelen/GSoC2017_PhotometricCalib_Sample_Data/";
+    // The path for the images used for response calibration
+    string imageFolderPath = userPrefix + "response_calib/images";
+    // The yaml file which contains the timestamps and exposure times for each image used for camera response calibration
+    string timePath = userPrefix + "response_calib/times.yaml";
+
+    // Construct a photometric_calib::ResponseCalib object by giving path of image, path of time file and specify the format of images
+    photometric_calib::ResponseCalib resCal(imageFolderPath, timePath, "jpg");
+
+    // Debug mode will generate some temporary data
+    bool debug = true;
+    // Calibration of camera response function begins
+    resCal.calib(debug);
+
+    // The result and some intermediate data are stored in the folder ./photoCalibResult in which
+    // pcalib.yaml is the camera response function file
+    // Since we are using debug mode, we can visualize the response function:
+    Mat invRes = imread("./photoCalibResult/G-10.png", CV_LOAD_IMAGE_UNCHANGED);
+    // As shown as Fig.3 in the paper from J.Engel, et al. in the paper A Photometrically Calibrated Benchmark For Monocular Visual Odometry
+    imshow("Inverse Response Function", invRes);
+    waitKey(0);
+
+    // To see the response-calibrated image, we can use GammaRemover
+    Mat oriImg = imread(imageFolderPath + "/00480.jpg", CV_LOAD_IMAGE_UNCHANGED);
+    photometric_calib::GammaRemover gammaRemover("./photoCalibResult/pcalib.yaml", oriImg.cols, oriImg.rows);
+    Mat caliImg = gammaRemover.getUnGammaImageMat(oriImg);
+    imshow("Original Image", oriImg);
+    waitKey(0);
+    imshow("Gamma Removed Image", caliImg);
+    waitKey(0);
+
+    return 0;
+}