BUG: Fix conversion from 1 to LA (#2175)

Closes #2165
Closes #2176

Author: pubpub-zz

pypdf/filters.py

@@ -1097,6 +1097,8 @@ def _handle_jpx(
                 alpha = alpha.convert("L")
             if img.mode == "P":
                 img = img.convert("RGB")
+            elif img.mode == "1":
+                img = img.convert("L")
             img.putalpha(alpha)
         if "JPEG" in image_format:
             extension = ".jp2"

tests/test_filters.py

@@ -594,3 +594,13 @@ def test_encodedstream_lookup():
     name = "iss2124.pdf"
     reader = PdfReader(BytesIO(get_data_from_url(url, name=name)))
     reader.pages[12].images[0]
+
+
+@pytest.mark.enable_socket()
+def test_convert_1_to_la():
+    """From #2165"""
+    url = "https://github.com/py-pdf/pypdf/files/12543290/whitepaper.WBT.token.blockchain.whitepaper.pdf"
+    name = "iss2165.pdf"
+    reader = PdfReader(BytesIO(get_data_from_url(url, name=name)))
+    for i in reader.pages[13].images:
+        _ = i