Identification of PDF preservation risks with Apache Preflight: the sequel 25 Jul 2013

Last winter I started a first attempt at identifying preservation risks in PDF files using the Apache Preflight PDF/A validator. This work was later followed up by others in two SPRUCE hackathons in Leeds (see this blog post by Peter Cliff) and London (described here). Much of this later work tacitly assumes that Apache Preflight is able to successfully identify features in PDF that are a potential risk for long-term access. This Wiki page on uses and abuses of Preflight (created as part of the final SPRUCE hackathon) even goes as far as stating that “Preflight is thorough and unforgiving (as it should be)”. But what evidence do we have to support such claims? The only evidence that I’m aware of, are the results obtained from a small test corpus of custom-created PDFs. Each PDF in this corpus was created in such a way that it includes only one specific feature that is a potential preservation risk (e.g. encryption, non-embedded fonts, and so on). However, PDFs that exist ‘in the wild’ are usually more complex. Also, the PDF specification often allows you to implement similar features in subtly different ways. For these reasons, it is essential to obtain additional evidence of Preflight’s ability to detect ‘risky’ features before relying on this tool in any operational setting.

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ICC profiles and resolution in JP2: update on 2011 D-Lib paper 01 Jul 2013

It’s been more than two years now since I wrote my D-Lib paper JPEG 2000 for Long-term Preservation: JP2 as a Preservation Format. From time to time people ask me about the status of the issues that are mentioned in that paper, so here’s a long overdue update.

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EPUB for archival preservation: an update 23 May 2013


Last year (2012) the KB released a report on the suitability of the EPUB format for archival preservation. A substantial number of EPUB-related developments have happened since then, and as a result some of the report’s findings and conclusions have become outdated. This applies in particular to the observations on EPUB 3, and the support of EPUB by characterisation tools. This blog post provides an update to those findings. It addresses the following topics in particular:

  • Use of EPUB in scholarly publishing
  • Adoption and use of EPUB 3
  • EPUB 3 reader support
  • Support of EPUB by characterisation tools

In the following sections I will briefly summarise the main developments in each of these areas, after which I will wrap up things in a concluding section.

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Adventures in Debian packaging 23 Apr 2013

About a year ago, work started on packaging SCAPE tools. Jpylyzer was the first SCAPE tool that was turned into a Debian package. Some time later, the OPF set up a couple of machine images at Amazon Web Services, which can be used to create packages repeatedly using a virtual machine. Even though I’ve used the Amazon service a couple of times myself, I really know next to nothing about Debian packages, and it’s safe to say that the underlying build process has been more or less a complete mystery to me.

To get a better understanding of the process for building Debian packages, I had a try at packaging jpylyzer on my local machine (which runs on Linux Mint 14). Some time ago Dave Tarrant and Rui Castro wrote a nice step-by-step guide on building Debian packages on the OPF Wiki, so I tried to follow the instructions there. While working on this, I made some notes, mainly to remind myself of what I was doing. Then I realised that some of this might be useful to others as well, so I decided to turn it into a blog post.

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What do we mean by "embedded" files in PDF? 09 Jan 2013

The most important new feature of the recently released PDF/A-3 standard is that, unlike PDF/A-2 and PDF/A-1, it allows you to embed any file you like. Whether this is a good thing or not is the subject of some heated on-line discussions. But what do we actually mean by embedded files? As it turns out, the answer to this question isn’t as straightforward as you might think. One of the reasons for this is that in colloquial use we often talk about “embedded files” to describe the inclusion of any “non-text” element in a PDF (e.g. an image, a video or a file attachment). On the other hand, the word “embedded files” in the PDF standards (including PDF/A) refers to something much more specific, which is closely tied to PDF’s internal structure.

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