--- /dev/null
+/*****************************************************************************************************
+USAGE:
+./opencv_annotation -images <folder location> -annotations <ouput file>
+
+Created by: Puttemans Steven
+*****************************************************************************************************/
+
+#include <opencv2/core.hpp>
+#include <opencv2/highgui.hpp>
+#include <opencv2/imgcodecs.hpp>
+#include <opencv2/videoio.hpp>
+#include <opencv2/imgproc.hpp>
+
+#include <fstream>
+#include <iostream>
+
+using namespace std;
+using namespace cv;
+
+// Function prototypes
+void on_mouse(int, int, int, int, void*);
+string int2string(int);
+void get_annotations(Mat, stringstream*);
+
+// Public parameters
+Mat image;
+int roi_x0 = 0, roi_y0 = 0, roi_x1 = 0, roi_y1 = 0, num_of_rec = 0;
+bool start_draw = false;
+
+// Window name for visualisation purposes
+const string window_name="OpenCV Based Annotation Tool";
+
+// FUNCTION : Mouse response for selecting objects in images
+// If left button is clicked, start drawing a rectangle as long as mouse moves
+// Stop drawing once a new left click is detected by the on_mouse function
+void on_mouse(int event, int x, int y, int , void * )
+{
+ // Action when left button is clicked
+ if(event == EVENT_LBUTTONDOWN)
+ {
+ if(!start_draw)
+ {
+ roi_x0 = x;
+ roi_y0 = y;
+ start_draw = true;
+ } else {
+ roi_x1 = x;
+ roi_y1 = y;
+ start_draw = false;
+ }
+ }
+ // Action when mouse is moving
+ if((event == EVENT_MOUSEMOVE) && start_draw)
+ {
+ // Redraw bounding box for annotation
+ Mat current_view;
+ image.copyTo(current_view);
+ rectangle(current_view, Point(roi_x0,roi_y0), Point(x,y), Scalar(0,0,255));
+ imshow(window_name, current_view);
+ }
+}
+
+// FUNCTION : snippet to convert an integer value to a string using a clean function
+// instead of creating a stringstream each time inside the main code
+string int2string(int num)
+{
+ stringstream temp_stream;
+ temp_stream << num;
+ return temp_stream.str();
+}
+
+// FUNCTION : given an image containing positive object instances, add all the object
+// annotations to a known stringstream
+void get_annotations(Mat input_image, stringstream* output_stream)
+{
+ // Make it possible to exit the annotation
+ bool stop = false;
+
+ // Reset the num_of_rec element at each iteration
+ // Make sure the global image is set to the current image
+ num_of_rec = 0;
+ image = input_image;
+
+ // Init window interface and couple mouse actions
+ namedWindow(window_name, WINDOW_AUTOSIZE);
+ setMouseCallback(window_name, on_mouse);
+
+ imshow(window_name, image);
+ stringstream temp_stream;
+ int key_pressed = 0;
+
+ do
+ {
+ // Keys for processing
+ // You need to select one for confirming a selection and one to continue to the next image
+ // Based on the universal ASCII code of the keystroke: http://www.asciitable.com/
+ // c = 99 add rectangle to current image
+ // n = 110 save added rectangles and show next image
+ // <ESC> = 27 exit program
+ key_pressed = 0xFF & waitKey(0);
+ switch( key_pressed )
+ {
+ case 27:
+ destroyWindow(window_name);
+ stop = true;
+ case 99:
+ // Add a rectangle to the list
+ num_of_rec++;
+ // Draw initiated from top left corner
+ if(roi_x0<roi_x1 && roi_y0<roi_y1)
+ {
+ temp_stream << " " << int2string(roi_x0) << " " << int2string(roi_y0) << " " << int2string(roi_x1-roi_x0) << " " << int2string(roi_y1-roi_y0);
+ }
+ // Draw initiated from bottom right corner
+ if(roi_x0>roi_x1 && roi_y0>roi_y1)
+ {
+ temp_stream << " " << int2string(roi_x1) << " " << int2string(roi_y1) << " " << int2string(roi_x0-roi_x1) << " " << int2string(roi_y0-roi_y1);
+ }
+ // Draw initiated from top right corner
+ if(roi_x0>roi_x1 && roi_y0<roi_y1)
+ {
+ temp_stream << " " << int2string(roi_x1) << " " << int2string(roi_y0) << " " << int2string(roi_x0-roi_x1) << " " << int2string(roi_y1-roi_y0);
+ }
+ // Draw initiated from bottom left corner
+ if(roi_x0<roi_x1 && roi_y0>roi_y1)
+ {
+ temp_stream << " " << int2string(roi_x0) << " " << int2string(roi_y1) << " " << int2string(roi_x1-roi_x0) << " " << int2string(roi_y0-roi_y1);
+ }
+
+ rectangle(input_image, Point(roi_x0,roi_y0), Point(roi_x1,roi_y1), Scalar(0,255,0), 1);
+
+ break;
+ }
+
+ // Check if escape has been pressed
+ if(stop)
+ {
+ break;
+ }
+ }
+ // Continue as long as the next image key has not been pressed
+ while(key_pressed != 110);
+
+ // If there are annotations AND the next image key is pressed
+ // Write the image annotations to the file
+ if(num_of_rec>0 && key_pressed==110)
+ {
+ *output_stream << " " << num_of_rec << temp_stream.str() << endl;
+ }
+
+ // Close down the window
+ destroyWindow(window_name);
+}
+
+int main( int argc, const char** argv )
+{
+ // Read in the input arguments
+ string image_folder;
+ string annotations;
+ for(int i = 1; i < argc; ++i )
+ {
+ if( !strcmp( argv[i], "-images" ) )
+ {
+ image_folder = argv[++i];
+ }
+ else if( !strcmp( argv[i], "-annotations" ) )
+ {
+ annotations = argv[++i];
+ }
+ }
+
+ // Create the outputfilestream
+ ofstream output(annotations.c_str());
+
+ // Return the image filenames inside the image folder
+ vector<String> filenames;
+ String folder(image_folder);
+ glob(folder, filenames);
+
+ // Loop through each image stored in the images folder
+ // Create and temporarily store the annotations
+ // At the end write everything to the annotations file
+ for (size_t i = 0; i < filenames.size(); i++){
+ // Read in an image
+ Mat current_image = imread(filenames[i]);
+
+ // Perform annotations & generate corresponding output
+ stringstream output_stream;
+ get_annotations(current_image, &output_stream);
+
+ // Store the annotations, write to the output file
+ if (output_stream.str() != ""){
+ output << filenames[i] << output_stream.str();
+ }
+ }
+
+ return 0;
+}