Prerequisites

Software

• UNIX shell, e.g. Windows Subsystem for Linux with Ubuntu (tested with WSL/Ubuntu 22.04 LTS and Debian 11 on the tape server)

• Tesseract OCR (tested with version 4.1.x)

• muPDF tools (tested with version 1.17)

• GhostScript (tested with version 9.53)

Make sure the versions of tesseract, muPDF and GhostScript are up to date. Run the following command on your command line to update software components of your Linux installation:

...

1. Navigate to the staging directory containing the Production Master (_pm) image files

2. Create temporary subdirectories 'pdf' and 'pdf/pages', and navigate back to the staging directory:

   Code Block
   language bash
   mkdir pdf cd pdf mkdir pages cd ..

   Run tesseract OCR on all images in the staging directory: 

   Code Block
   language bash
   for i in *.tif; do tesseract -c tessedit_page_number=0 -l eng $i pdf/pages/${i%_pm.tif} pdf; done

3. Merge page-level PDF documents into one PDF per volume/issue:

   Code Block
   language bash
   mutool merge -o pdf/combined-pdf.pdf pdf/pages/*.pdf

4. Produce the final PDF document.

   Code Block
   language bash
   gs -sDEVICE=pdfwrite \ -dPDFA=2 \ -dPDFACompatibilityPolicy=1 \ -dNOSAFER \ -dFastWebView \ -sColorConversionStrategy=RGB \ -dDownsampleColorImages=true \ -dColorImageDownsampleThreshold=1.0 \ -dAutoRotatePages=/None \    -dColorImageResolution=150 -o downsampled-pdf.pdf /mnt/dps/staff_workspaces/mirko/pdfa/PDFA_def_UTL.ps combined-pdf.pdf

5. Delete the pdf subfolder and combined-pdf.pdf