Mmh, thanks Steve, I was unaware of this. There is no "1.4.0" OpenJpeg version available from their site (no such SVN tag for example).

Do you think OpenJpeg is that bad in reliability/quality to be used by ClearCanvas ? Which are the most common bugs or undesired behaviors ?

I really need some available jpeg 2000 codec, but besides choosing the encoder/decoder, what is the most difficult for me to understand is how to code the ClearCanvas codec (IDicomCodec), if in C#. I guess the C++ jpeg 2000 codec is still accurate (conformant to Dicom standards, ftp://medical.nema.org/medical/dicom/2009/09_05pu3.pdf para. 8.2.4). I have no C++ knowlegde so wonder about updating OpenJpeg files, compiling codec and testing it again...

In the near future I think I will integrate some other jpeg 2000 coding/decoding tool, so it would be fine to be able to write the ClearCanvas codec part. I guess I need to read some specific standard specification about retrieving decompressed pixel data to fill the DicomUncompressedPixelData object.

Thanks for your opinion/help.

Barbara

Barbara,

At the time we had OpenJpeg integrated, we discovered that when we did lossless compression of very noisy ultrasound images, in some cases we could not decompress the image back to the original. Ie, the compression was not truly lossless. We decided to give up on OpenJpeg at that time, although we decided to leave the codec in our repository. One other comment is that the actual code we were using was quite slow for compression and decompression. If you would take the risk of using OpenJpeg, you would just have to test the codec with enough image types that you're expecting to see with your application that you think it functions properly.

As for the OpenJpeg versions itself, I've followed the mailing list for OpenJpeg, and there's definitely been more activity lately on the library, but I haven't seen any "official" releases of the product, it seems like they're just doing development. I'm unsure about the 1.4 version.

As for seeing examples of how the codec is written and pixel data accessed, you should be able to look at the RLE codec, its written in c#...

Steve

Thanks Steve.

So it's just a communication problem from OpenJpeg. In this post I give you some details I got from their project state : www.clearcanvas.ca/dnn/Community/Fo...aspx#18694

Hi Steve,

Version 1.4 of OpenJPEG was released last month. I've looked through the list of recent changes that came with it, but can't see anything obviously related to fixes to lossless compression/decompression problems. There is a 'new' issue on their website related to lossless encoding of 16 bit grey images - it doesn't mention problems on the decoding side.

So I was wondering, when you were doing the OpenJPEG work with CC, were you able to determine if the problem was on the compression or decompression side?

I am interested in adding Jpeg2000 support to the Workstation, purely for viewing some existing Jpeg2000 DICOM studies from a legacy system. A properly working decoder would be fine for that.

Thanks,

Gary