Six ways to decode a lossy JP2

26 September 2014

Some time ago Will Palmer, Peter May and Peter Cliff of the British Library published a really interesting paper that investigated three different JPEG 2000 codecs, and their effects on image quality in response to lossy compression. Most remarkably, their analysis revealed differences not only in the way these codecs encode (compress) an image, but also in the decoding phase. In other words: reading the same lossy JP2 produced different results depending on which implementation was used to decode it.

A limitation of the paper’s methodology is that it obscures the individual effects of the encoding and decoding components, since both are essentially lumped in the analysis. Thus, it’s not clear how much of the observed degradation in image quality is caused by the compression, and how much by the decoding. This made me wonder how similar the decode results of different codecs really are.


Jpylyzer software finalist voor digitale duurzaamheidsprijs

11 September 2014

Vandaag maakte de Britse Digital Preservation Coalition de finalisten bekend die in de race zijn voor de Digital Preservation Awards 2014. Deze prijs is in 2004 in het leven geroepen om aandacht te vestigen op initiatieven die een belangrijke bijdrage leveren aan het toegankelijk houden van digitaal erfgoed.


When (not) to migrate a PDF to PDF/A

27 August 2014

It is well-known that PDF documents can contain features that are preservation risks (e.g. see here and here). Migration of existing PDFs to PDF/A is sometimes advocated as a strategy for mitigating these risks. However, the benefits of this approach are often questionable, and the migration process can also be quite risky in itself. As I often get questions on this subject, I thought it might be worthwhile to do a short write-up on this.


How to save a web page to the Internet Archive

02 August 2014

This short tutorial shows how to take a snapshot of a web page, and save it to the Internet Archive’s Wayback Machine.


Why can't we have digital preservation tools that just work?

31 January 2014

One of my first blogs here covered an evaluation of a number of format identification tools. One of the more surprising results of that work was that out of the five tools that were tested, no less than four of them (FITS, DROID, Fido and JHOVE2) failed to even run when executed with their associated launcher script. In many cases the Windows launcher scripts (batch files) only worked when executed from the installation folder. Apart from making things unnecessarily difficult for the user, this also completely flies in the face of all existing conventions on command-line interface design. Around the time of this work (summer 2011) I had been in contact with the developers of all the evaluated tools, and until last week I thought those issues were a thing of the past. Well, was I wrong!



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