community[patch]: Handle gray scale images in ImageBlobParser (Fixes 30261 and 29586) (#30493)

Fix [29586](https://github.com/langchain-ai/langchain/issues/29586) and
[30261](https://github.com/langchain-ai/langchain/pull/30261)

libs/community/langchain_community/document_loaders/parsers/images.py

@@ -53,7 +53,11 @@ class BaseImageBlobParser(BaseBlobParser):
 
         with blob.as_bytes_io() as buf:
             if blob.mimetype == "application/x-npy":
-                img = Img.fromarray(numpy.load(buf))
+                array = numpy.load(buf)
+                if array.ndim == 3 and array.shape[2] == 1:  # Grayscale image
+                    img = Img.fromarray(numpy.squeeze(array, axis=2), mode="L")
+                else:
+                    img = Img.fromarray(array)
             else:
                 img = Img.open(buf)
             content = self._analyze_image(img)

libs/community/tests/integration_tests/document_loaders/parsers/test_images.py

@@ -1,7 +1,9 @@
 import re
+from io import BytesIO
 from pathlib import Path
 from typing import Any, Type
 
+import numpy as np
 import pytest
 from langchain_core.documents.base import Blob
 from langchain_core.language_models import FakeMessagesListChatModel
@@ -18,12 +20,13 @@ building_image = Blob.from_path(path_base / "examples/building.jpg")
 text_image = Blob.from_path(path_base / "examples/text.png")
 page_image = Blob.from_path(path_base / "examples/page.png")
 
+_re_in_image = r"(?ms).*MAKE.*TEXT.*STAND.*OUT.*FROM.*"
+
 
 @pytest.mark.parametrize(
     "blob,body",
     [
-        (building_image, ""),
+        (Blob.from_path(path_base / "examples/text-gray.png"), _re_in_image),
-        (text_image, r"(?ms).*MAKE.*TEXT.*STAND.*OUT.*FROM.*BACKGROUNDS.*"),
     ],
 )
 @pytest.mark.parametrize(
@@ -58,3 +61,39 @@ def test_image_parser_with_differents_files(
     documents = list(blob_loader(**kw).lazy_parse(blob))
     assert len(documents) == 1
     assert re.compile(body).match(documents[0].page_content)
+
+
+@pytest.mark.parametrize(
+    "blob_loader,kw",
+    [
+        (RapidOCRBlobParser, {}),
+        (TesseractBlobParser, {}),
+        (
+            LLMImageBlobParser,
+            {
+                "model": FakeMessagesListChatModel(
+                    responses=[
+                        ChatMessage(
+                            id="ai1",
+                            role="system",
+                            content="A building. MAKE TEXT STAND  OUT FROM BACKGROUNDS",
+                        ),
+                    ]
+                )
+            },
+        ),
+    ],
+)
+def test_image_parser_with_numpy(
+    blob_loader: Type,
+    kw: dict[str, Any],
+) -> None:
+    gray_image = np.empty(shape=(412, 1652, 1))
+    with BytesIO() as buffer:
+        np.save(buffer, gray_image)
+        buffer.seek(0)
+        npy_bytes = buffer.getvalue()
+
+    blob = Blob.from_data(npy_bytes, mime_type="application/x-npy")
+    documents = list(blob_loader(**kw).lazy_parse(blob))
+    assert len(documents) == 1