Fix deprecated module and attribute errors in visualization and plot utils

Python/src/main.py

@@ -92,4 +92,4 @@ def create_args():
             print("Please specify the path to the video meta csv file.")
             sys.exit(1)
         visualization_plot = VisualizationPlot(created_arguments, tracks, static_info, meta_dictionary)
-        visualization_plot.show()
+        visualization_plot.show()

Python/src/utils/plot_utils.py

@@ -20,8 +20,7 @@ def set_val(self, val):
             self.val = val
             if not self.eventson:
                 return
-            for cid, func in self.observers.items():
-                func(discrete_val)
+            self._observers.process('changed',discrete_val)
 
     def update_val_external(self, val):
         self.set_val(val)

Python/src/visualization/visualize_frame.py

@@ -1,6 +1,7 @@
 import os
 import scipy.ndimage
 import matplotlib as mpl
+from matplotlib.pyplot import imread
 
 from data_management.read_csv import *
 
@@ -36,7 +37,7 @@ def __init__(self, arguments, read_tracks, static_info, meta_dictionary, fig=Non
         background_image_path = arguments["background_image"]
         if background_image_path is not None and os.path.exists(background_image_path):
             # Plot the image
-            self.background_image = scipy.ndimage.imread(background_image_path)
+            self.background_image = imread(background_image_path)
             self.y_sign = 1
             im = self.background_image[:, :, :]
             self.ax.imshow(im)