lossy jpeg compression results in large blocky artifacts

[mthomas]

Hi everyone - 

We're testing a dcm4chee installation with jpeg lossy compression turned on ( [cuid=1.2.840.10008.5.1.4.1.1.2]JPLY(0.99:JPEG Lossy Compression:15.0) ) in the storeSCP. The compression seems to work, but the results are not visually acceptable. Even the image viewer in the dcm4chee web interface cannot display the images correctly. We're running a 32 bit java VM, platform is Windows 64 Home Premium. dcm4chee version is 2.0.27. Lossless jpeg 2000 works fine. I've attached the original, compressed (using dcm4chee) and uncompressed (using gdcmconv) images here. They are from assourancetourix, the CT dataset made available on the osirix site. I used the original never compressed version. But I've seen this problem with all images (I've only tested CT so far) I've sent to the storeSCP. I've scoured the internet looking for other people with similar problems, and haven't found anything. So I'm thinking it is my setup. Also, I've tried looking at the compressed and (gdcmconv) uncompressed images with other viewer viewers such as ClearCanvas and IrfanView, and they show the same result.

The attached files are: im-tst.dcm, which is the original. 19b5d445.dcm which is what dcm4chee produces after compression. And 2outmod.dcm is the result of gdcmconv uncompression.

Thanks for your help.

Mathew

[mthomas]

Attached is a jpg of the output image, as seen in IrfanView.

[fleetwoodfc]

What is the expected output?

[Mathew Thomas]

Hi, thanks for responding. Attached is what it is supposed to look like. There is nothing wrong with the header data, as far as I've seen.

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[mthomas]

Hi again- maybe I'll ask a simpler question - 

Does 12 bit jpeg lossy compression work for everyone who has tried it? I'm only talking about the compression on receipt, not the delayed compression. I'm using version 2.0.27. I know there was a defect associated with this a while back. I wonder if it is in my version?

Thanks again. 

On Thursday, March 27, 2014 9:46:12 AM UTC-4, mthomas wrote:

[mthomas]

Hi again - 

It seems like this exact same issue was observed and fixed a while ago. See the link here http://forums.dcm4che.org/jiveforums/thread.jspa?threadID=3126&tstart=0&messageID=20573#20573.

But I still see artifacts in the rendered image. Was this really resolved? Is there a special step to invoke the new code? Is anyone out there using lossy jpeg compression?

I am using dcm4chee-2.17.2 on Windows 64 bit.

Thanks!

Mathew

On Thursday, March 27, 2014 9:46:12 AM UTC-4, mthomas wrote: