OCR-all.sh

Description

OCR-all.sh is a script designed to process PDF files in specified directories using OCR (Optical Character Recognition) on macOS. The script activates iTerm (or any terminal of your choice), sources zsh configuration, and processes each PDF file found in the input directory. The processed files are saved in the output directory, and the original files are moved to the trash. This script uses OCRmyPDF for OCR processing.

Prerequisites

Before running this script, ensure you have the following prerequisites installed and configured:

• zsh: The script is written to run in zsh.
• iTerm: The script activates iTerm using AppleScript. You can replace iTerm with your terminal of choice.
• OCRmyPDF: The OCR processing is handled by OCRmyPDF, which should be installed and accessible at /opt/homebrew/bin/ocrmypdf.
• Homebrew: Install Homebrew if not already installed to easily manage packages like OCRmyPDF.
• trash-cli: The script uses the trash command to move processed files to the trash. Ensure it is installed and configured.

Installation

1. Install Homebrew (if not already installed):

   /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

   For more details, visit the Homebrew installation page.

2. Install OCRmyPDF:

   brew install ocrmypdf

3. Install trash-cli:

   brew install trash

Usage

1. Set the Input and Output Directories: Modify the INPUT_DIR and OUTPUT_DIR variables in the script to point to the desired input and output directories. The Input directory should contain subdirectories which are named according to the three-letter language codes of the languages you want to process the child PDF files with.

   INPUT_DIR="/your/input/parent/directory/containing/language-directories"
   OUTPUT_DIR="/your/output/directory"

2. Run the Script: Ensure the script has execute permissions and then run it.

   chmod +x OCR-all.sh
   ./OCR-all.sh

Script Details

• Input Directory: The script processes all subdirectories within the specified INPUT_DIR. Each subdirectory is expected to be named after the language code for OCR processing and should contain PDF files (not image-format files). Multiple languages can be used in the directory names, separated by a plus sign (+), e.g., eng+spa.
• Output Directory: Processed files are saved in the OUTPUT_DIR with _ocr appended to the filename.
• OCR Processing: Uses ocrmypdf with the following options:
  • --jobs 6: Run 6 OCR jobs in parallel.
  • -l "$lang_code": Specify the language code for OCR.
  • --tesseract-oem 3: Use the Tesseract OCR engine mode 3.
  • --output-type pdf: Output the processed file as a PDF.
  • --tesseract-timeout 600: Set a timeout of 600 seconds for Tesseract.
  • --force-ocr: Force OCR on all input files.
  • --jbig2-lossy: Use JBIG2 lossy compression for monochrome images.
  • --optimize 3: Optimize the output PDF to reduce size.

Documentation

For more information on OCRmyPDF, please refer to the OCRmyPDF documentation.

Language Packs

For optimal OCR performance, it is recommended to install tessdata_best language packs. Instructions for installing language packs can be found here. The recommended language packs can be downloaded from the Tesseract OCR GitHub page, which includes a table of available language codes.

License

This project is licensed under the Creative Commons Zero v1.0 Universal (CC0 1.0) Public Domain Dedication. You can copy, modify, distribute, and perform the work, even for commercial purposes, all without asking permission.

Acknowledgments

Special thanks to the developers of OCRmyPDF and trash-cli for their tools that made this script possible.