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OwlOCR MCP

Python 3.11+ macOS License: MIT

MCP (Model Context Protocol) server for PDF and image OCR on macOS. Supports two backends:

  • OwlOCR CLI - Higher accuracy (recommended)

  • Vision Framework - No external dependencies

Features

  • πŸ“„ PDF OCR - Extract text from PDF files page by page with separators

  • πŸ–ΌοΈ Image OCR - Extract text from PNG, JPEG, and other image formats

  • 🌏 Multi-language - Korean + English by default (configurable)

  • πŸ”„ Dual Backend - Auto-selects OwlOCR if available, falls back to Vision Framework

  • ⚑ Async - Non-blocking execution for MCP clients

Benchmark Results

Tested on a 4-page Korean theological document with Hebrew text:

Metric

Vision Framework

OwlOCR CLI

Time

9.87s

9.30s

Time/Page

2.47s

2.33s

Word Accuracy

85.62%

91.79%

Character Accuracy

94.46%

95.07%

Winner: OwlOCR CLI - Faster and more accurate.

Requirements

  • macOS (uses Apple Vision Framework / OwlOCR.app)

  • Python 3.11+

  • OwlOCR.app (optional, for better accuracy)

Installation

git clone https://github.com/yourusername/owlocr-mcp.git cd owlocr-mcp uv sync

Using pip

git clone https://github.com/yourusername/owlocr-mcp.git cd owlocr-mcp pip install -e .

MCP Client Configuration

Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json:

{ "mcpServers": { "owlocr": { "command": "uv", "args": ["run", "--directory", "/path/to/owlocr-mcp", "owlocr-mcp"] } } }

Generic MCP Client

{ "mcpServers": { "owlocr": { "command": "/path/to/owlocr-mcp/.venv/bin/python", "args": ["-m", "owlocr_mcp.server"] } } }

Available Tools

ocr_pdf_to_text

Extract text from a PDF file.

Parameters:

Parameter

Type

Default

Description

pdf_path

string

required

Absolute path to the PDF file

pages

list[int]

null

Page numbers to process (1-based). If null, all pages

dpi

int

200

Resolution for rendering. Higher = better quality but slower

backend

string

"auto"

"auto", "owlocr", or "vision"

languages

list[string]

null

Language codes (Vision only). Default: ["ko-KR", "en-US"]

Example:

Extract text from /Users/me/document.pdf using OwlOCR

Output:

첫 번째 νŽ˜μ΄μ§€ λ‚΄μš©... ===== Page 2 ===== 두 번째 νŽ˜μ΄μ§€ λ‚΄μš©... --- OCR Complete: 2 page(s) processed using OwlOCR CLI ---

ocr_image_to_text

Extract text from an image file.

Parameters:

Parameter

Type

Default

Description

image_path

string

required

Absolute path to the image file

backend

string

"auto"

"auto", "owlocr", or "vision"

languages

list[string]

null

Language codes (Vision only)

check_ocr_backends

Check available OCR backends on the system.

Output:

OCR Backend Status: βœ… Vision Framework: Available (macOS built-in) βœ… OwlOCR CLI: Available (/Applications/OwlOCR.app) Recommendation: Use backend='owlocr' for best accuracy

Backend Selection

Backend

Accuracy

Speed

Requirements

owlocr

⭐⭐⭐⭐⭐

⭐⭐⭐⭐

OwlOCR.app installed

vision

⭐⭐⭐⭐

⭐⭐⭐⭐

None (macOS built-in)

auto

Best available

-

Uses OwlOCR if available

Running the Benchmark

Compare backends on your own PDF:

# Both backends uv run python benchmark.py /path/to/your.pdf # With accuracy comparison (requires ground truth) uv run python benchmark.py /path/to/your.pdf --show-text # Specific backend only uv run python benchmark.py /path/to/your.pdf --method owlocr uv run python benchmark.py /path/to/your.pdf --method vision

Project Structure

owlocr-mcp/ β”œβ”€β”€ src/owlocr_mcp/ β”‚ β”œβ”€β”€ __init__.py β”‚ β”œβ”€β”€ server.py # MCP server with tools β”‚ β”œβ”€β”€ ocr.py # Vision Framework backend β”‚ β”œβ”€β”€ ocr_owlocr.py # OwlOCR CLI backend β”‚ └── pdf.py # PDF processing utilities β”œβ”€β”€ benchmark.py # Performance comparison script β”œβ”€β”€ pyproject.toml └── README.md

How It Works

OwlOCR Backend

  1. Render PDF pages to PNG using pypdfium2

  2. Copy images to OwlOCR sandbox: ~/Library/Containers/JonLuca-DeCaro.OwlOCR/Data/tmp/

  3. Run CLI: /Applications/OwlOCR.app/Contents/MacOS/OwlOCR --cli --input <file>

  4. Combine results with page separators

Vision Framework Backend

  1. Render PDF pages to PNG using pypdfium2

  2. Load as CIImage via PyObjC

  3. Create VNRecognizeTextRequest with accurate recognition level

  4. Process with VNImageRequestHandler

  5. Sort results by position and combine

Troubleshooting

"OwlOCR.app not found"

Install OwlOCR from owlocr.com or use backend="vision".

File picker dialog appears

This happens when OwlOCR can't access files outside its sandbox. The MCP server handles this by copying files to the sandbox temp directory automatically.

Poor accuracy on specific languages

For Vision Framework, specify languages explicitly:

ocr_pdf_to_text(pdf_path, languages=["ja-JP", "en-US"])

Supported language codes: ko-KR, en-US, ja-JP, zh-Hans, zh-Hant, etc.

License

MIT License - see LICENSE file.

Acknowledgments

-
security - not tested
A
license - permissive license
-
quality - not tested

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