Read image with IMREAD_GRAYSCALE and add getImage() method

Author: nynyg

modules/photometric_calib/include/opencv2/photometric_calib/Reader.hpp

@@ -41,6 +41,14 @@ class CV_EXPORTS Reader
     unsigned long getNumImages() const;
 
 
+    /*!
+     * @brief Given the id of the image and return the image. id is in fact just the index of the image in the
+     * vector contains all the images.
+     * @param id
+     * @return Mat of the id^th image.
+     */
+    Mat getImage(unsigned long id) const;
+
     /*!
      * @brief Given the id of the image and return its timestamp value. id is in fact just the index of the image in the
      * vector contains all the images.

modules/photometric_calib/src/Reader.cpp

@@ -56,7 +56,7 @@ Reader::Reader(const std::string &folderPath, const std::string &timesPath)
     // images should be of CV_8U and same size
     for(size_t i = 0; i < images.size(); ++i)
     {
-        Mat img = imread(images[i]);
+        Mat img = imread(images[i], IMREAD_GRAYSCALE);
         CV_Assert(img.type() == CV_8U);
         if(i == 0)
         {
@@ -72,6 +72,12 @@ Reader::Reader(const std::string &folderPath, const std::string &timesPath)
     _folderPath = folderPath;
 }
 
+Mat Reader::getImage(unsigned long id) const
+{
+    CV_Assert(id < images.size());
+    return imread(images[id], IMREAD_GRAYSCALE);
+}
+
 double Reader::getTimestamp(unsigned long id) const
 {
     CV_Assert(id < timeStamps.size());