adding a universal OpenCV based annotation tool for cascade classifier training

diff --git a/apps/annotation/opencv_annotation.cpp b/apps/annotation/opencv_annotation.cpp
new file mode 100644 (file)
index 0000000..fac1aeb
--- /dev/null
+++ b/apps/annotation/opencv_annotation.cpp
@@ -0,0 +1,191 @@
+/*****************************************************************************************************
+USAGE:
+./opencv_annotation -images <folder location> -annotations <ouput file>
+
+Created by: Puttemans Steven
+*****************************************************************************************************/
+
+#include <opencv2/core/core.hpp>
+#include <opencv2/highgui/highgui.hpp>
+#include <opencv2/imgproc/imgproc.hpp>
+
+#include <fstream>
+#include <iostream>
+
+using namespace std;
+using namespace cv;
+
+// 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 flag, void* param)
+{
+    // Action when left button is clicked
+    if(event == CV_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 == CV_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 = 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 (int 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;
+}