Compressing Images after their arrival.

roozbeh007 · Post by **roozbeh007** » Mon Mar 09, 2009 4:37 am

we have a GE QXI 4 slice CT. on average there is 250 instances & 120 mb per study. I have set "Compress images received from this AE" to "JPEG Lossless Transfer Syntax". but it doesn't seems to have any effect on total study size. am i doing this right? what is the best compression method here?

we have a AIRIS II also but the size of studies barely goes over 15-20 MB.

here is an example:
CT of Brain. 137 Images. 70 MB
MRI of LSP. 64 Images. 8.12 MB.

I understand maybe AIRIS is sending the images in a better compression format than QXI does, but how can I optimize the CT images for better storage? thanks.

Post by **pacsone** » Mon Mar 09, 2009 5:18 pm

The original study size will not change after the Post-Receive Image Compression feature has been enabled, as the design goal of the feature is to trade storage space for faster transfer speed when delivering images to the web-based viewers. i.e., when a Dicom study is received by PacsOne Server and the Post-Receive Image Compression is enabled, PacsOne Server will compress all images of the received study using the user-specified Dicom compression transfer syntax (with the original study intact) as soon as the images are received. When the web-based viewers (e.g., RemotEye, Radscaper, etc) request for the Dicom study, PacsOne Server will send the pre-compressed images to the viewers instead of the original/uncompressed versions, thus the transfer speed will be much faster since they are pre-compressed with much smaller image sizes.

After the compression, both the original and the compressed versions of the images are stored by PacsOne Server, and it will deliver the compressed instead of the original images to the web-based viewers to achieve faster transfer speed, i.e., this is the trade in of the additional storage space (for the compressed images) for the faster transfer speed when delivering images to the web viewers.

roozbeh007 · Post by **roozbeh007** » Mon Mar 09, 2009 11:32 pm

So basically not only this will not save me any space, it will take more space as it now has 2 sets of same study with different compression format. Thanks for the heads up.

Post by **pacsone** » Tue Mar 10, 2009 12:15 am

If you want to save storage space, you may want to configure the sending AEs so that they propose one of the Dicom compression transfer syntaxes (see the following list) when sending images to PacsOne Server. Currently, PacsOne supports the following Dicom compression transfer syntaxes:

JPEG Lossless
JPEG Lossy Baseline
JPEG Lossy Extended
RLE Lossless
JPEG2000 Part-1 Lossless Only
JPEG2000 Part-1 Lossless or Lossy

For more information, please refer to our Dicom Conformance Statement online:

http://www.pacsone.net/conformance.htm