diff --git a/inkycal/main.py b/inkycal/main.py
index 499fb65..727c597 100644
--- a/inkycal/main.py
+++ b/inkycal/main.py
@@ -6,7 +6,10 @@ Main class for inkycal Project
 Copyright by aceisace
 """
 
+import glob
+import hashlib
 import json
+import os
 import traceback
 from logging.handlers import RotatingFileHandler
 
@@ -168,6 +171,9 @@ class Inkycal:
         # Path to store images
         self.image_folder = image_folder
 
+        # Remove old hashes
+        self._remove_hashes(self.image_folder)
+
         # Give an OK message
         print('loaded inkycal')
 
@@ -235,6 +241,45 @@ class Inkycal:
 
         self._assemble()
 
+    def _image_hash(self, _in):
+        """Create a md5sum of a path or a bytes stream."""
+        if not isinstance(_in, str):
+            image_bytes = _in.tobytes()
+        else:
+            try:
+                with open(_in) as i:
+                    return i.read()
+            except FileNotFoundError:
+                image_bytes = None
+        return hashlib.md5(image_bytes).hexdigest() if image_bytes else ""
+
+    def _remove_hashes(self, basepath):
+        for _file in glob.glob(f"{basepath}/*.hash"):
+            try:
+                os.remove(_file)
+            except:
+                pass
+
+    def _write_image_hash(self, path, _in):
+        """Write hash to a file."""
+        with open(path, "w") as o:
+            o.write(self._image_hash(_in))
+
+    def _needs_image_update(self, _list):
+        """Check if any image has been updated or not.
+        Input a list of tuples(str, image)."""
+        res = False
+        for item in _list:
+            _a = self._image_hash(item[0])
+            _b = self._image_hash(item[1])
+            print("{f1}:{h1} -> {h2}".format(f1=item[0], h1=_a, h2=_b))
+            if _a != _b:
+                res = True
+                self._write_image_hash(item[0], item[1])
+            print("Refresh needed: {a}".format(a=res))
+        return res
+
+
     def run(self):
         """Runs main program in nonstop mode.
 
@@ -264,7 +309,10 @@ class Inkycal:
             errors = []  # store module numbers in here
 
             # short info for info-section
-            self.info = f"{current_time.format('D MMM @ HH:mm')}  "
+            if not self.settings.get('image_hash', False):
+                self.info = f"{current_time.format('D MMM @ HH:mm')}  "
+            else:
+                self.info = ""
 
             for number in range(1, self._module_number):
 
@@ -299,6 +347,9 @@ class Inkycal:
                 display = self.Display
 
                 self._calibration_check()
+                if self._calibration_state:
+                    # after calibration we have to forcefully rewrite the screen
+                    self._remove_hashes(self.image_folder)
 
                 if self.supports_colour:
                     im_black = Image.open(f"{self.image_folder}canvas.png")
@@ -310,7 +361,12 @@ class Inkycal:
                         im_colour = upside_down(im_colour)
 
                     # render the image on the display
-                    display.render(im_black, im_colour)
+                    if not self.settings.get('image_hash', False) or self._needs_image_update([
+                      (f"{self.image_folder}/canvas.png.hash", im_black),
+                      (f"{self.image_folder}/canvas_colour.png.hash", im_colour)
+                    ]):
+                        # render the image on the display
+                        display.render(im_black, im_colour)
 
                 # Part for black-white ePapers
                 elif not self.supports_colour:
@@ -321,7 +377,10 @@ class Inkycal:
                     if self.settings['orientation'] == 180:
                         im_black = upside_down(im_black)
 
-                    display.render(im_black)
+                    if not self.settings.get('image_hash', False) or self._needs_image_update([
+                      (f"{self.image_folder}/canvas.png.hash", im_black),
+                    ]):
+                        display.render(im_black)
 
             print(f'\nNo errors since {counter} display updates \n'
                   f'program started {runtime.humanize()}')