docs: add Ollama local VLM guide

README.md

@@ -52,6 +52,18 @@ parsemux parse doc.pdf --extract-images --describe-images --vlm-key sk-...
 Provider is auto-detected from key prefix (`sk-` → OpenAI, `sk-ant-` → Anthropic, `AI` → Google).
 Default models: gpt-5.4-nano, claude-haiku-4.5, gemini-2.5-flash, qwen2.5vl:7b (local).
 
+### Ollama local VLM
+
+For free local image description, install Ollama and pull the default local vision model:
+
+```bash
+ollama pull qwen2.5vl:7b
+parsemux parse doc.pdf --extract-images --describe-images
+```
+
+When no VLM key is provided, parsemux falls back to Ollama automatically.
+See [docs/ollama-guide.md](docs/ollama-guide.md) for setup details and performance notes.
+
 ### Start your own server
 
 ```bash

docs/ollama-guide.md

@@ -0,0 +1,50 @@
+# Ollama local VLM guide
+
+Use Ollama when you want free, local image description for extracted document images.
+
+## Install Ollama
+
+1. Install Ollama from <https://ollama.com/download>.
+2. Start the Ollama service on your machine.
+3. Pull the default local vision model used by parsemux:
+
+```bash
+ollama pull qwen2.5vl:7b
+```
+
+Parsemux defaults to `qwen2.5vl:7b` for local image description.
+
+## Run parsemux with local image description
+
+When you do not provide `--vlm-key` or `--llm-key`, parsemux auto-detects the VLM provider as Ollama.
+
+```bash
+parsemux parse doc.pdf --extract-images --describe-images
+```
+
+This flow:
+
+- extracts images from the document
+- sends them to the local Ollama server at `http://localhost:11434`
+- writes image descriptions back into the parse result
+
+You can also set the provider explicitly:
+
+```bash
+parsemux parse doc.pdf --extract-images --describe-images --vlm-provider ollama
+```
+
+## Performance expectations
+
+Ollama is the zero-cost option, but it trades speed for privacy and local control.
+
+- Speed: slower than hosted APIs, especially on CPU-only machines
+- Quality: good enough for many document images, charts, and screenshots, but usually below top cloud vision models
+- Privacy: best option when documents must stay on your machine
+- Cost: `0.0` direct API cost inside parsemux
+
+For best results:
+
+- use a machine with a capable GPU if available
+- keep document batches small when testing locally
+- expect longer runtimes for image-heavy PDFs