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I have a PDF that I want to show to someone without giving them the ability to copy it. One possible way would be to convert pages to images, then these back into a PDF. How can I use convert or pdftk or otherwise script? Not GUI.

  • 2
    Often they will still be able to simply run OCR and copy the text anyway. Just saying. – Revetahw says Reinstate Monica Nov 3 '16 at 18:36
  • In fact my ASUS laptop came with Foxit PhantomPDF viewer/printer. One time it upgraded itself over the net, and there was a limited time free trial feature activated that did OCR. Worked quite nicely changing a scan-only PDF into something I could search and cut/paste from (but I'm still too cheap to buy a new copy) – infixed Nov 3 '16 at 20:40
  • Adding security options to a pdf document to make it uncopyable/unprintable/unviewable under certain circumstances is built into the file format, you just have to enable it. I've only done this with Acrobat though, I can't recommend a package to do it via script. I'm interested to see if anyone else knows of one. – Cody Nov 3 '16 at 21:15
  • This is a security by obscurity problem. They will always have the ability to copy your text regardless of what you do to try and stop them. At best you can make it very difficult, but never impossible – Darren H Nov 4 '16 at 4:43
  • "at best you can make it very difficult": that's an interesting programming problem, maybe the software can add noise that would confuse OCR programs but it's pretty much invisible to humans. Still not a solution though, they can just pay a data entry person to get it out as text. – sundar - Reinstate Monica Nov 4 '16 at 14:25
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Imagemagick rasterizes everything. You could simply do:

convert -density 200 input.pdf output.pdf

Of course the recipient might decide to run an OCR program on your file. The density parameter sets the resolution expressed as PPI.

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PDF to Image

The poppler-utils packages includes the pdftoppm utility, capable of converting PDF files to either ppm, png or jpeg format:

pdftoppm -png file.pdf prefix

This will make files name prefix-X.extension where X is the page number (each file outputted will be one page of the PDF converted) and where extension is whatever output type you choose.

By default the resolution is 150dpi. You can increase the resolution (for higher quality output) by using this command:

pdftoppm -rx 300 -ry 300 -extension file.pdf prefix

And to print only one page, do:

pdftoppm -f N -singlefile -extension file.pdf prefix

where N is the page number, starting with 1.

This method is a lot faster and less clunky than using the imagemagick package as mentioned in other posts. Although you do have to use it to convert back.

Image to PDF

This requires the installation of the imagemagick package. To do this, do:

sudo apt-get install imagemagick

The imagemagick package has a utility called convert which will do just as it is named; convert. To make use of it in the way that you want, run it like so:

convert file.extension file.pdf

This will make a PDF of only that single page, though. To combine all outputs of the previous command for converting to images, use this command:

convert *.extension file.pdf

This will grab all files in the directory that you are in with the extension extension and convert them into a PDF file named file.pdf.

Note

I chose to format my answer in the way of two separate commands as to give the OP flexibility and understanding of the task that they are trying to complete, instead of one command linking the two. Of course, if that solution is better for them, then I encourage them to upvote/mark as answered that particular answer.

  • Suggesting a way to split the task in two parts is good for flexibility. But it may be noted that the first part can be done with convert as well. :) – Andrea Lazzarotto Nov 3 '16 at 15:04
  • @AndreaLazzarotto I know that it can. But, I chose pdftoppm because it is faster and lighter than convert. I just went the route of most efficient and only used convert because there was no reverse command for pdftoppm. – TheOdd Nov 3 '16 at 15:07
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I always use pdftoppm to convert pdf to png images. simply execute the following command

pdftoppm -f [startpage] -l [end page] -r [resolution (use 300 or 600) -png <pdf file location> [Prefix for your image files]

and then execute

convert prefix-[number].png file.pdf

but there are programs that convert these images back into text. making your pdf uncopyable is very hard. You could add an encryption protection to prevent copying and printing which will make is (slightly) more difficult to copy and print your pdf file

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