Moved a function to this class, more fitting.

utils/utility.py

@@ -20,6 +20,16 @@ class Utilities:
         except PermissionError as e:
             print(f"Error saving setings: {e}")
 
+    def append_number_to_name(self, base_name: str, current_image: int, total_images: int, invert: bool):
+            """"Returns name, combination of base_name and ending number."""
+            total_digits = len(str(total_images))
+            if invert:
+                ending_number = total_images - (current_image - 1)
+            else:
+                ending_number = current_image
+            ending = f"{ending_number:0{total_digits}}"
+            return f"{base_name}_{ending}"
+
     def yes_no(self, str):
         """Ask user y/n question"""
         while True: