The following procedure succeeded in enabling Jpeg2000 (JP2) format images
to be served out of DSpace 7.2, under the new IIIF support with the
Cantaloupe 5 image server installed and items enabled with the specifically
added metadata value 'dspace.iiif.enabled ' and a value of 'true' set.
This is a web server running under Ubuntu 20.04.
It took me a while to understand that with iiif, it is this new image
server which delivers images to the client. DSpace is showing the user an
iiif enabled item and the Mirador viewer has requested a default display of
the image (from Cantaloupe). The user then may choose a full screen view or
any other sort of zoom level. The viewer makes updated requests to the
Cantaloupe image server and it responds with the new data.
This has all worked fine for my DS7.2 install, except our limited storage
has prevented uploading large size image files. The JPEG2000 format is very
efficient in multiple resolution images and is capable of amazing levels of
good looking compression ratios, so this seemed to be the best option for
us to support IIIF. It didn't work with our default installation. Here is
how we fixed it:
The mime type 'image/jp2' is not defined in the DSpace Bitstream Format
registry. Without defining this, you will not be able to serve the images.
1.
(Logged in as administrator) go to Registries > Format. This opens
the Bitstream Format Registry.
2.
(Green button) “Add a new bitstream format”.
3.
(add the following) Name = image/jp2, MIME Type = image/jp2,
Description = Jpeg2000, File extensions = jp2 (save)
This will allow the image to be properly recognized when added to the item.
Your server now probably needs libraries to tell the Cantaloupe image
server how to deal with the jpeg2000 images. My site has installed the
OpenJpeg libraries, with the following command:
apt install libopenjp2-7 libopenjp2-tools -y
Now edit the cantaloupe.properties configuration file. Mine is located at
/opt/cantaloupe_config .
vi /opt/cantaloupe_config/cantaloupe.properties
Edit this file to define the following
a) processor.selection_strategy = ManualSelectionStrategy
b) processor.ManualSelectionStrategy.jp2 = OpenJpegProcessor
c) OpenJpegProcessor.path_to_binaries = /usr/bin/opj_decompress
7. (Save the file)
8. (restart Cantaloupe) systemctl restart cantaloupe.service
You may check Cantaloupe's status by the command =
systemctl status cantaloupe.service
and see a returning message, like:
( Format.JPEG2000:
com.sun.media.imageioimpl.plugins.jpeg2000.J2KImageWriter )
You may now create new items and add bitstream images of the jp2 format.
CAUTION, it is not all that common to have transcoding software that can
produce compatible jp2. Some of my utilities claim they can but they do not
work with DSpace. I have been having good luck using Irfanview and even
ImageMagick. Much more experimentation is needed here to create the
perfect, zoomable image. I hope this is a useful start for those
interested.
Thank you so much to Mohammad S. AlMutairi and Tim Donohue for providing
critical information in getting this to work!
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