Thumbnail from a PDF file containing JPEG2000 encoded images

[Technologiczny Informator]

Hello everyone,

DSpace 7.6 users reported an issue with an empty thumbnail of the deposited PDF file. Analysis of the problem showed an error in the log - several entries in a row about the content:

ERROR unknown unknown org.apache.pdfbox.contentstream.PDFStreamEngine @ Cannot read JPEG2000 image: Java Advanced Imaging (JAI) Image I/O Tools are not installed

As I understand it, the deposited PDF file contains images in JPEG2000 format and therefore DSpace has a problem generating the correct thumbnail.

How can we get out of this situation? Thank you in advance for any suggestions.

Regards,
Mariusz

[Technologiczny Informator]

Nobody had such a problem?

[DSpace Technical Support]

Hi, 

As you noted, it sounds like the issue is that the PDF has embedded JPEG2000 images.  That error seems to be thrown by PDFBox, which is the library DSpace uses to index and create thumbnails from PDFs (by default).

It sounds like the issue is that PDFBox won't create thumbnails for JPEG2000 images unless you install more libraries.  Here's what looks like the solution from StackOverflow. https://stackoverflow.com/questions/57707735/how-to-fix-cannot-read-jpeg2000-image-java-advanced-imaging-jai-image-i-o-to   You'd likely have to add additional dependencies to DSpace's main "pom.xml" (alongside the "org.apache.pdfbox" dependencies already listed there).  

That'd require rebuilding / redeploying DSpace to ensure these new dependencies are installed on your backend.  I'm not sure if it'd work immediately after rebuilding, or if more changes would be needed. (As I've never tried this before and not yet seen this error.)

Or, alternatively, you could try to use the ImageMagick Media Filters, which can also create thumbnails from PDFs.  In this situation you'd disable the default "PDFBox JPEG Thumbnail" filter and enable ImageMagick instead as described here: https://wiki.lyrasis.org/display/DSDOC7x/ImageMagick+Media+Filters   That PDF thumbnail converter might have an easier time with JPEG2000 images (I admit though that I haven't tested it).

Tim