refactor: make dpi explicit on convert_pdf_to_image for dedup with unstructured (#501)

## Summary

- Make `dpi` an explicit parameter (default 200) on
`convert_pdf_to_image` instead of reading
`inference_config.PDF_RENDER_DPI` internally
- Enables unstructured to import and call this function directly,
eliminating the duplicate `_render_pdf_pages` implementation
- No behavior change — both internal callers already pass `dpi`
explicitly

## Changelog

```
## 1.6.2

### Enhancement
- Make `dpi` an explicit parameter on `convert_pdf_to_image` (default 200) instead of reading from config internally, enabling unstructured to use this as the single source of truth for PDF rendering
```

## Depends on / blocks

- Blocks Unstructured-IO/unstructured#4315 (dedup of PDF rendering)
- Blocks Unstructured-IO/core-product#1480 (version bump)

Author: KRRT7

CHANGELOG.md

@@ -1,3 +1,8 @@
+## 1.6.2
+
+### Enhancement
+- Make `dpi` an explicit parameter on `convert_pdf_to_image` (default 200) instead of reading from config internally, enabling unstructured to use this as the single source of truth for PDF rendering
+
 ## 1.6.1
 
 ### Enhancement

unstructured_inference/__version__.py

@@ -1 +1 @@
-__version__ = "1.6.1"  # pragma: no cover
+__version__ = "1.6.2"  # pragma: no cover

unstructured_inference/config.py

@@ -116,10 +116,5 @@ def IMG_PROCESSOR_SHORTEST_EDGE(self) -> int:
         """configuration for DetrImageProcessor to scale images"""
         return self._get_int("IMG_PROCESSOR_SHORTEST_EDGE", 800)
 
-    @property
-    def PDF_RENDER_DPI(self) -> int:
-        """DPI to render PDF pages to images"""
-        return self._get_int("PDF_RENDER_DPI", 350)
-
 
 inference_config = InferenceConfig()

unstructured_inference/inference/layout.py

@@ -11,7 +11,6 @@
 import pypdfium2 as pdfium
 from PIL import Image, ImageSequence
 
-from unstructured_inference.config import inference_config
 from unstructured_inference.inference.elements import (
     TextRegion,
 )
@@ -412,15 +411,17 @@ def process_file_with_model(
 def convert_pdf_to_image(
     filename: Optional[str] = None,
     file: Optional[Union[bytes, BinaryIO]] = None,
-    dpi: Optional[int] = None,
+    dpi: int = 200,
     output_folder: Optional[Union[str, PurePath]] = None,
     path_only: bool = False,
     first_page: Optional[int] = None,
     last_page: Optional[int] = None,
     password: Optional[str] = None,
 ) -> Union[List[Image.Image], List[str]]:
-    """
-    Centralized function to render PDF pages using pypdfium.
+    """Render PDF pages to PIL images or saved PNGs using pypdfium2.
+
+    This is the single source of truth for PDF→image rendering across unstructured
+    and unstructured-inference. Callers should pass their own DPI value explicitly.
     """
     if path_only and not output_folder:
         raise ValueError("output_folder must be specified if path_only is true")
@@ -430,8 +431,6 @@ def convert_pdf_to_image(
         assert Path(output_folder).exists()
         assert Path(output_folder).is_dir()
 
-    if dpi is None:
-        dpi = inference_config.PDF_RENDER_DPI
     scale = dpi / 72.0
 
     with _pdfium_lock: