imagemagick needs fiddling

[wwwutz]

this is some known issue, so I might include ImageMagick ...

[2024-02-26 09:23:35,494] [ERROR] [paperless.parsing] Unable to make thumbnail with convert: Convert failed at ['convert', '-density', '300', '-scale', '500x5000>', '-alpha', 'remove', '-strip', '-auto-orient', '-define', 'pdf:use-cropbox=true', '/tmp/paperless/wwwutz/2.5.3/paperless-t9o8kr8f/archive.pdf[0]', '/tmp/paperless/wwwutz/2.5.3/paperless-t9o8kr8f/convert.webp']

[2024-02-26 09:23:35,494] [WARNING] [paperless.parsing] Thumbnail generation with ImageMagick failed, falling back to ghostscript. Check your /etc/ImageMagick-x/policy.xml!

[wwwutz]

paperless@server:~/2.5.3$ grep -i pdf /etc/ImageMagick-6/policy.xml
  <!-- <policy domain="module" rights="read|write" pattern="{PS,PDF,XPS}" /> -->
  <policy domain="coder" rights="none" pattern="PDF" />

ref: https://github.com/paperless-ngx/paperless-ngx/issues/895

[wwwutz]

graphicsmagick does not know about -alpha

paperless@server:~/2.5.3/paperless-ngx$ convert -density 300 -scale 500x5000 -alpha remove -strip -auto-orient -define 'pdf:use-cropbox=true' /home/data/scratch/ticketdirect-1.pdf /home/data/scratch/lala.webp
convert convert: Unrecognized option (-alpha).
paperless@server:~/2.5.3/paperless-ngx$ dpkg -S /usr/bin/convert
graphicsmagick-imagemagick-compat: /usr/bin/convert