About the format
From https://www.file-extensions.org/
... The ND2 format uses JPEG-2000 compression, and also can be
uncompressed or Zip-compressed ...
As mentioned in read jpeg2000 files in java
JPEG 2000 seems to be not included inside standard Java SDK.
Potential solutions
1. Use Open JPEG + existing JNI wrapper
I would try out https://github.com/uclouvain/openjpeg and search for some java wrappers to use openjpeg (e.g. look at https://github.com/barmintor/openjpeg for an JNI approach for maven).
2. Use Open JPEG + Write own JNI wrapper
Another approach would be to look at
https://github.com/ThalesGroup/JP2ForAndroid/blob/master/library/src/main/java/com/gemalto/jp2/JP2Decoder.java , inspect involved classes etc. and write an own JNI wrapper
The mentioned github reposoitory code writes to android bitmap, so not directly usable for your Swing project, but it shows you the way to decode JPEG2000 format by native calls to OpenJPEG library
How to convert a byte[] to a BufferedImage in Java? describes conversion from byte array to a buffered image - so these information should help you to read the image data into a buffered image (so usable in Swing).