skipping already watermarked files

app/watermark.py

@@ -17,8 +17,9 @@ def watermark_text(input_image_path: str,
 
     black = (3, 8, 12)
     white = (254, 254, 254)
+    yellow = (237,255,33)
     font = ImageFont.truetype(font_path, size, encoding='unic')
-    drawing.text(pos, text=text, fill=white, font=font, anchor="la")
+    drawing.text(pos, text=text, fill=yellow, font=font, anchor="la")
     if show:
         photo.show()
     photo.save(output_image_path)

main.py

@@ -38,9 +38,12 @@ if __name__ == '__main__':
         files = _find_all_files(args.input_folder, args.file_mask)
         print(f"files={files}")
         for file in files:
+            newfilename = _build_output_filename(file)
+            if os.path.isfile(newfilename):
+                continue
             watermark_text_bottom_right(
                 input_image_path=file, 
-                output_image_path=_build_output_filename(file), 
+                output_image_path=newfilename, 
                 text=args.text, 
                 font_path=args.font, 
                 pos=(1000, 200),