Extracting Slide Images from a Pdf

01 October 2014

codemsbuild

Being a programmer, I’m often tempted to crack open a compiler when faced with a task that involves anything to do with computers.

In this case, I needed to create a some screenshots of the slides from a presentation. Unfortunately the presentation document was only available as a pdf. This left me with the choice of crafting a solution myself or in finding an already existing tool or coercing a set of tools to do the work.

Now I had a vague recollection that Inkscape could import a pdf file. On investigating the command line reference, it seems that Inkscape can import a pdf and export an image from it.

Inkscape.exe slidedeck.pdf --export-png=slidedeck.png

Great. Except that it only works with the first page in the document.

So what I needed is a tool to take a multi-page pdf and split it into single pages. Which is exactly what Coherent Pdf Tools are able to do. Like this

cpdf.exe -split slidedeck.pdf -o slidedeck%%%%.pdf

Which generates a sequence of single page pdfs, numbered 01.pdf upwards.

Once I had the syntax of the two command line building blocks I used a bit of MsBuild batching magic to handle the conversion of each individual page into an image.

Update

Now I’ve been playing with this technique for a number of different slide decks, I discovered that any pdf with embedded fonts didn’t export correctly. The font was replaced by Inkscape with a weird “not understood” icon.

Clearly another approach was needed. After some googling, I discovered another tool, pdf2svg which could export pdfs to svg and could handle embedded fonts.

pdf2svg.exe slide01.pdf slide01.png 1

Fortunately, but unsurprisingly, Inkscape is so awesome it can handle conversion from svg to png.

Inkscape.exe -f slide01.svg -e slide01.png

So the script has had to change a little to include the extra tool in the chain. It now goes….

Multi-page-pdf -> batch-single-page-pdfs -> batch-single-svgs -> batch-single-pngs

I have refreshed the gist above to reflect this new information.

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