OCRmyPDF — Core OCR Guide Skill

OCRmyPDF — Core OCR Guide

Overview

OCRmyPDF adds an OCR text layer to scanned PDF files, allowing them to be searched or copy-pasted. It uses Tesseract OCR, supports 100+ languages, produces PDF/A by default, and distributes work across all CPU cores.

For image processing (deskew, rotate, clean), see the ocrmypdf-image skill. For optimization and PDF/A options, see ocrmypdf-optimize. For batch/Docker/scripting, see ocrmypdf-batch. For Python API and plugins, see ocrmypdf-api.

Installation

One-liner installs (recommended)

| OS | Command | |----|---------| | Debian / Ubuntu | apt install ocrmypdf | | Fedora | dnf install ocrmypdf tesseract-osd | | macOS (Homebrew) | brew install ocrmypdf | | macOS (MacPorts) | port install ocrmypdf | | FreeBSD | pkg install py-ocrmypdf | | Snap | snap install ocrmypdf |

pip install (latest version)

# After installing system dependencies (Tesseract, Ghostscript)
pip install ocrmypdf

Verify

ocrmypdf --version
ocrmypdf --help

Requirements

Python 3.11+
Tesseract 4.1.1+ (OCR engine)
Ghostscript 9.54+ or pypdfium2 (PDF rasterization)
Optional: jbig2enc (compression), pngquant (image optimization), unpaper (cleaning)

Quick Start

# Basic OCR — input scanned PDF, output searchable PDF/A
ocrmypdf input.pdf output.pdf

# OCR an image file directly
ocrmypdf --image-dpi 300 scan.png output.pdf

# OCR in place (only overwrites on success)
ocrmypdf myfile.pdf myfile.pdf

Language Support

OCRmyPDF uses Tesseract language packs. Install them for your OS:

# Debian / Ubuntu
apt-cache search tesseract-ocr          # List all language packs
apt install tesseract-ocr-chi-sim       # Chinese Simplified
apt install tesseract-ocr-fra           # French

# macOS (Homebrew)
brew install tesseract-lang             # All languages

# Fedora
dnf search tesseract-langpack
dnf install tesseract-langpack-ita      # Italian

Using languages

# Single language
ocrmypdf -l fra document.pdf output.pdf

# Multiple languages
ocrmypdf -l eng+fra bilingual.pdf output.pdf

# Chinese Simplified + English
ocrmypdf -l chi_sim+eng chinese-doc.pdf output.pdf

Note: Use ISO 639-3 codes for language identifiers.

OCR Modes

Default mode (skip existing text)

# Skip pages that already have text — only OCR pages without text
ocrmypdf input.pdf output.pdf

Force OCR (`--force-ocr` or `-m force`)

# Rasterize and OCR all pages, even those with existing text
ocrmypdf --force-ocr input.pdf output.pdf
# v17+ short form:
ocrmypdf -m force input.pdf output.pdf

Redo OCR (`--redo-ocr` or `-m redo`)

# Replace existing OCR without rasterizing (preserves quality)
ocrmypdf --redo-ocr input.pdf output.pdf
# v17+ short form:
ocrmypdf -m redo input.pdf output.pdf

Skip text (`--skip-text` or `-m skip`)

# Skip pages with any text, only OCR blank/image pages
ocrmypdf --skip-text input.pdf output.pdf
# v17+ short form:
ocrmypdf -m skip input.pdf output.pdf

No OCR (image processing only)

# Apply image processing / PDF/A conversion without OCR
ocrmypdf --ocr-engine none input.pdf output.pdf

Page Selection

# OCR only specific pages
ocrmypdf --pages 1,3,5-10 input.pdf output.pdf

# OCR only the first page, minimal changes elsewhere
ocrmypdf --pages 1 --output-type pdf --optimize 0 input.pdf output.pdf

Output Types

# PDF/A (default) — for archival
ocrmypdf --output-type pdfa input.pdf output.pdf

# Standard PDF
ocrmypdf --output-type pdf input.pdf output.pdf

# Auto (v17+) — speculative PDF/A, falls back to standard PDF
ocrmypdf --output-type auto input.pdf output.pdf

# No output PDF — only produce sidecar text
ocrmypdf --output-type none --sidecar text.txt input.pdf -

Sidecar Text File

# Produce a companion text file with OCR text
ocrmypdf --sidecar output.txt input.pdf output.pdf

Metadata

# Set output PDF metadata
ocrmypdf --title "My Document" --author "Author Name" --subject "Subject" input.pdf output.pdf

Parallel Processing

# Use 4 CPU cores (default: all available)
ocrmypdf --jobs 4 input.pdf output.pdf

# Single-threaded
ocrmypdf --jobs 1 input.pdf output.pdf

Common Recipes

Make a scanned PDF searchable

ocrmypdf scanned.pdf searchable.pdf

Convert image to searchable PDF

ocrmypdf --image-dpi 300 scan.jpg output.pdf

OCR a multilingual document

ocrmypdf -l eng+deu+fra multilingual.pdf output.pdf

Re-OCR with newer Tesseract

ocrmypdf --redo-ocr old-ocr.pdf updated.pdf

Strip all text/OCR from a PDF

ocrmypdf --ocr-engine none --force-ocr input.pdf stripped.pdf

Quick Reference

| Task | Command | |------|---------| | Basic OCR | ocrmypdf input.pdf output.pdf | | Specify language | ocrmypdf -l fra input.pdf output.pdf | | Multiple languages | ocrmypdf -l eng+fra input.pdf output.pdf | | Force re-OCR all pages | ocrmypdf --force-ocr input.pdf output.pdf | | Replace existing OCR | ocrmypdf --redo-ocr input.pdf output.pdf | | Skip pages with text | ocrmypdf --skip-text input.pdf output.pdf | | Specific pages only | ocrmypdf --pages 1,3,5-10 input.pdf output.pdf | | Output standard PDF | ocrmypdf --output-type pdf input.pdf output.pdf | | Extract text sidecar | ocrmypdf --sidecar text.txt input.pdf output.pdf | | Image to PDF | ocrmypdf --image-dpi 300 image.png output.pdf | | In-place OCR | ocrmypdf myfile.pdf myfile.pdf | | Set metadata | ocrmypdf --title "Title" input.pdf output.pdf | | Parallel jobs | ocrmypdf --jobs 4 input.pdf output.pdf |

Troubleshooting

"Tesseract not found": Install Tesseract and ensure it's on PATH.
Poor OCR quality: Check language packs (-l), try --deskew (see ocrmypdf-image), or --oversample 300.
"Input file has text": Use --force-ocr, --redo-ocr, or --skip-text as appropriate.
Large output files: See ocrmypdf-optimize for --optimize levels and JBIG2.
Signed PDFs: Use --invalidate-digital-signatures to override (signatures will be invalidated).

Agent Skills: OCRmyPDF — Core OCR Guide

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