MAINT: Remove duplicate CCITT processing (#3415)

Author: j-t-1

pypdf/filters.py

@@ -796,15 +796,15 @@ def decode_stream_data(stream: Any) -> bytes:
     return data
 
 
-def _xobj_to_image(x_object_obj: dict[str, Any]) -> tuple[Optional[str], bytes, Any]:
+def _xobj_to_image(x_object: dict[str, Any]) -> tuple[Optional[str], bytes, Any]:
     """
     Users need to have the pillow package installed.
 
     It's unclear if pypdf will keep this function here, hence it's private.
     It might get removed at any point.
 
     Args:
-      x_object_obj:
+      x_object:
 
     Returns:
         Tuple[file extension, bytes, PIL.Image.Image]
@@ -822,20 +822,20 @@ def _xobj_to_image(x_object_obj: dict[str, Any]) -> tuple[Optional[str], bytes,
 
     def _apply_alpha(
         img: Image.Image,
-        x_object_obj: dict[str, Any],
+        x_object: dict[str, Any],
         obj_as_text: str,
         image_format: str,
         extension: str,
     ) -> tuple[Image.Image, str, str]:
         alpha = None
-        if IA.S_MASK in x_object_obj:  # add alpha channel
-            alpha = _xobj_to_image(x_object_obj[IA.S_MASK])[2]
+        if IA.S_MASK in x_object:  # add alpha channel
+            alpha = _xobj_to_image(x_object[IA.S_MASK])[2]
             if img.size != alpha.size:
                 logger_warning(
                     f"image and mask size not matching: {obj_as_text}", __name__
                 )
             else:
-                # TODO : implement mask
+                # TODO: implement mask
                 if alpha.mode != "L":
                     alpha = alpha.convert("L")
                 if img.mode == "P":
@@ -844,40 +844,40 @@ def _apply_alpha(
                     img = img.convert("L")
                 img.putalpha(alpha)
             if "JPEG" in image_format:
-                extension = ".jp2"
                 image_format = "JPEG2000"
+                extension = ".jp2"
             else:
-                extension = ".png"
                 image_format = "PNG"
+                extension = ".png"
         return img, extension, image_format
 
-    # for error reporting
+    # For error reporting
     obj_as_text = (
-        x_object_obj.indirect_reference.__repr__()
-        if x_object_obj is None  # pragma: no cover
-        else x_object_obj.__repr__()
+        x_object.indirect_reference.__repr__()
+        if x_object is None  # pragma: no cover
+        else x_object.__repr__()
     )
 
     # Get size and data
-    size = (cast(int, x_object_obj[IA.WIDTH]), cast(int, x_object_obj[IA.HEIGHT]))
-    data = x_object_obj.get_data()  # type: ignore
+    size = (cast(int, x_object[IA.WIDTH]), cast(int, x_object[IA.HEIGHT]))
+    data = x_object.get_data()  # type: ignore
     if isinstance(data, str):  # pragma: no cover
         data = data.encode()
     if len(data) % (size[0] * size[1]) == 1 and data[-1] == 0x0A:  # ie. '\n'
         data = data[:-1]
 
     # Get color properties
-    colors = x_object_obj.get("/Colors", 1)
-    color_space: Any = x_object_obj.get("/ColorSpace", NullObject()).get_object()
+    colors = x_object.get("/Colors", 1)
+    color_space: Any = x_object.get("/ColorSpace", NullObject()).get_object()
     if isinstance(color_space, list) and len(color_space) == 1:
         color_space = color_space[0].get_object()
 
-    mode, invert_color = _get_mode_and_invert_color(x_object_obj, colors, color_space)
+    mode, invert_color = _get_mode_and_invert_color(x_object, colors, color_space)
 
     # Get filters
-    filters = x_object_obj.get(SA.FILTER, NullObject()).get_object()
+    filters = x_object.get(SA.FILTER, NullObject()).get_object()
     lfilters = filters[-1] if isinstance(filters, list) else filters
-    decode_parms = x_object_obj.get(SA.DECODE_PARMS, None)
+    decode_parms = x_object.get(SA.DECODE_PARMS, None)
     if decode_parms and isinstance(decode_parms, (tuple, list)):
         decode_parms = decode_parms[0]
     else:
@@ -895,16 +895,16 @@ def _apply_alpha(
             colors,
             obj_as_text,
         )
-    elif lfilters in (FT.LZW_DECODE, FT.ASCII_85_DECODE, FT.CCITT_FAX_DECODE):
+    elif lfilters in (FT.LZW_DECODE, FT.ASCII_85_DECODE):
         # I'm not sure if the following logic is correct.
         # There might not be any relationship between the filters and the
         # extension
-        if lfilters in (FT.LZW_DECODE, FT.CCITT_FAX_DECODE):
-            extension = ".tiff"  # mime_type = "image/tiff"
+        if lfilters == FT.LZW_DECODE:
             image_format = "TIFF"
+            extension = ".tiff"  # mime_type = "image/tiff"
         else:
-            extension = ".png"  # mime_type = "image/png"
             image_format = "PNG"
+            extension = ".png"  # mime_type = "image/png"
         try:
             img = Image.open(BytesIO(data), formats=("TIFF", "PNG"))
         except UnidentifiedImageError:
@@ -938,7 +938,7 @@ def _apply_alpha(
             False,
         )
     elif mode == "":
-        raise PdfReadError(f"ColorSpace field not found in {x_object_obj}")
+        raise PdfReadError(f"ColorSpace field not found in {x_object}")
     else:
         img, image_format, extension, invert_color = (
             _extended_image_frombytes(mode, size, data),
@@ -947,9 +947,9 @@ def _apply_alpha(
             False,
         )
 
-    img = _apply_decode(img, x_object_obj, lfilters, color_space, invert_color)
+    img = _apply_decode(img, x_object, lfilters, color_space, invert_color)
     img, extension, image_format = _apply_alpha(
-        img, x_object_obj, obj_as_text, image_format, extension
+        img, x_object, obj_as_text, image_format, extension
     )
 
     if lfilters == FT.CCITT_FAX_DECODE and decode_parms.get("/BlackIs1", BooleanObject(False)).value is True: