Invert default document text extraction behavior

README.md

@@ -28,9 +28,17 @@ pip install -r requirements.txt
 
 Install these extras when you need richer file handling:
 
-- `PyPDF2` – enables text extraction from PDF attachments so their contents can be sent to the selected backend.
-- `python-docx` – parses DOCX files and pulls paragraph text for inclusion in prompts.
+- `PyPDF2` – used with `--extract-text` to pull PDF contents into prompts before sending them to the selected backend.
+- `python-docx` – used with `--extract-text` to parse DOCX files and include paragraph text inline.
 - `opencv-python` – extracts representative PNG frames from video files when using `--frame-by-frame` processing.
+- `pypdfium2` + `Pillow` – render PDFs into PNG previews that are uploaded to vision-capable backends when `--extract-text` is **not** supplied.
+- `Pillow` (alone) – renders DOCX snapshots so word-processing files can be viewed as images when skipping text extraction.
+
+Install the preview toolchain (for PDFs and DOCX files) with:
+
+```bash
+pip install pillow pypdfium2 python-docx
+```
 
 ## Usage
 
@@ -68,3 +76,10 @@ send extracted video frames individually and concatenate the responses.
 Use `-o`/`--output` to save the model response to a file. When no
 filename is supplied, the first attached file name with `.txt` appended is
 used; if no files are attached, `response.txt` is created.
+
+By default the CLI renders PDF and DOCX files into PNG preview images and sends
+those to vision-capable backends (such as Ollama multimodal models). When the
+preview toolchain is unavailable, the binary document is attached instead with a
+note explaining how to enable previews. Use `--extract-text` when you prefer to
+run local extraction tools (PDF via PyPDF2, DOCX via python-docx) before
+embedding the contents into the prompt.