Using ocrmypdf (with examples)
OCRmyPDF is a command-line tool used to generate searchable PDFs or PDF/A from scanned PDFs or images of text. It utilizes Optical Character Recognition (OCR) technology to extract text from images and convert it into searchable text within the PDF. In this article, we will explore several use cases of the ocrmypdf command and provide code examples for each.
Use Case 1: Creating a new searchable PDF/A file
The following code demonstrates how to create a new searchable PDF/A file from a scanned PDF or image file:
ocrmypdf path/to/input_file path/to/output.pdf
Motivation: This use case is useful when you have a scanned PDF or image file that you want to convert into a searchable PDF/A format. The OCR process will extract text from the scanned images and embed it into the PDF as searchable text.
Explanation:
path/to/input_file: The path to the input PDF or image file that you want to convert.path/to/output.pdf: The desired path and filename for the output PDF file.
Example Output: The command will process the input file and create a new PDF file at the specified output path. The resulting PDF will contain searchable text.
Use Case 2: Replacing a scanned PDF file with a searchable PDF file
The following code demonstrates how to replace a scanned PDF file with a searchable PDF file:
ocrmypdf path/to/file.pdf path/to/file.pdf
Motivation: This use case is useful when you have a scanned PDF file that you want to convert into a searchable PDF file without changing the filename or location. By specifying the same input and output paths, the command will overwrite the original file with the searchable version.
Explanation:
path/to/file.pdf: The path to the input scanned PDF file that you want to replace with a searchable PDF.
Example Output: The command will process the input file and overwrite it with a new version that contains searchable text.
Use Case 3: Skipping pages with existing text in a mixed-format input PDF file
The following code demonstrates how to skip pages in a mixed-format input PDF file that already contain text:
ocrmypdf --skip-text path/to/input.pdf path/to/output.pdf
Motivation: This use case is useful when working with mixed-format input PDF files that contain both scanned images and pages with existing searchable text. By using the --skip-text flag, the command will skip OCR processing on pages that already contain searchable text, reducing processing time.
Explanation:
--skip-text: The flag that indicates to skip OCR processing on pages with existing text.path/to/input.pdf: The path to the input PDF file that you want to process.path/to/output.pdf: The desired path and filename for the output PDF file.
Example Output: The command will process the input file, skipping OCR on pages with existing text and generating a new PDF file at the specified output path.
Use Case 4: Cleaning, de-skewing, and rotating pages of a poor scan
The following code demonstrates how to clean, de-skew, and rotate pages of a poor scan:
ocrmypdf --clean --deskew --rotate-pages path/to/input_file path/to/output.pdf
Motivation: This use case is useful when you have a poor scan with skewed or rotated pages. By using the --clean, --deskew, and --rotate-pages flags, the command will apply cleaning, de-skewing, and rotation algorithms to improve the quality of the scan.
Explanation:
--clean: The flag that enables cleaning of the input image.--deskew: The flag that enables de-skewing of the input image.--rotate-pages: The flag that enables automatic rotation of the input image based on the text orientation.
Example Output: The command will process the input file, apply cleaning, de-skewing, and rotation algorithms, and generate a new PDF file at the specified output path.
Use Case 5: Setting the metadata of the searchable PDF file
The following code demonstrates how to set the metadata of the searchable PDF file:
ocrmypdf --title "title" --author "author" --subject "subject" --keywords "keyword; key phrase; ..." path/to/input_file path/to/output.pdf
Motivation: This use case is useful when you want to add metadata to the searchable PDF file for better organization and searchability. By using the --title, --author, --subject, and --keywords flags, the command will set the corresponding metadata fields in the output PDF file.
Explanation:
--title "title": The title metadata for the output PDF.--author "author": The author metadata for the output PDF.--subject "subject": The subject metadata for the output PDF.--keywords "keyword; key phrase; ...": The keywords metadata for the output PDF. Multiple keywords can be provided, separated by semicolons.
Example Output: The command will process the input file, add the specified metadata to the output PDF, and generate a new PDF file at the specified output path.
Use Case 6: Displaying help
The following code demonstrates how to display help for the ocrmypdf command:
ocrmypdf --help
Motivation: This use case is useful when you need to refer to the command’s documentation for additional information or help with using the different options and flags available.
Example Output: The command will display the help message, providing information about the command’s usage, options, and flags.
Conclusion
In this article, we explored several use cases of the ocrmypdf command and provided code examples for each case. We learned how to create a new searchable PDF/A file, replace a scanned PDF file with a searchable version, skip pages with existing text in a mixed-format PDF, clean and enhance a poor scan, set metadata for the output PDF, and display help. By utilizing the ocrmypdf command, we can easily convert scanned PDFs or images of text into searchable and more manageable PDF files.
