Attempt to perform an operation not allowed by the security policy `PDF’
Change
<policy domain="coder" rights="none" pattern="PDF" />
to
<policy domain="coder" rights="read | write" pattern="PDF" />
in /etc/ImageMagick-?/policy.xml.
Tagpdfsandwich
pdfsandwich: OCR PDFs containing images
pdfsandwich is a handy tool developed by Tobias Elze for OCR’ing (via tesseract) scanned documents. Recognized text is added as an background layer, making it possible to search and index scanned documents.
pdfsandwich -lang eng+deu scanned.pdf