built-in compression findings of 1.4.16i

Hi,

Doing tests to compare compression settings after trying to compress an original CR image to below 500K size for document transfer.

1. The size output of built-in lossy compression( dicom.ini set LossyQuality = 50) does not result in any difference in file size from the default setting of LossyQuality = 95.

A. dicom.ini settings settings
DecompressNon16BitsJpeg = 1
UseBuiltInJPEG = 1

settings and the resulting file size
================================
uncompressed = 38.424 K
LossyQuality set at 95 = 7,462 k
LossyQuality set at 50 = 7,462 k

B. Using external program for compression (dcmcjpeg) dicom.ini settings
UseBuiltInJPEG = 0

using importconverter process with dcmcjpeg.exe -v +eb +g +q 50 parameters

settiings and the resulting file size
================================
set at 50 = 547 k

The test was does using a clean default server setup of 1.4.16i

C: I also obsserved that the image header of the compressed images do not indicate that a lossy compression was made sfter using jpeglossy of jpeg2000 lossy compression settings.
Header (0028,2110) CS [00] # 2 LossyImageCompression remains set to "0". I think k-pacs and iq-view uses this parameter because I get warnings when viewing images compressed from older conquest versions that were using dcmcjpeg.

saw this related post http://forum.dcmtk.org/viewtop…a9810bf07c18217d6e796f02c

I hope the observations can helps

ajgg

Hi,

Downloaded link and got ConquestUpdate1416j
the gui says latest built april-4-2012 but version (j)??

[CONQUESTSRV2] DGATE (1.4.16j, build Wed Apr 04 08:05:30 2012, bits 64) is running as threaded server

Tested with results on jpeg bug.
1. 2 LossyImageCompression is still not set to "01" with jk2000 (jl). works and sets its to "01" with jpeg lossy (j6)

result sample of (jl)
(0002,0010) UI [1.2.840.10008.1.2.4.91] # 22 TransferSyntaxUID
(0028,2110) CS [00] # 2 LossyImageCompression

Both jpeg lossless and lossy use [1.2.840.10008.1.2.4.91] # 22 TransferSyntaxUID. I undestand that this is accepted. Would using 1.2.840.10008.1.2.4.90 help distinguish lossless in the header.
2. LossyQuality in dicom.ini not working. Image size the same regarless of value both j6 and Jl

3. TransferSyntaxUID in dgatesop.lst remains hashed despite enabling jp3000 lossless or lossy after saving configuration in gui.

#JPEG2000LosslessOnly 1.2.840.10008.1.2.4.90 transfer LittleEndianExplicit
#JPEG2000 1.2.840.10008.1.2.4.91 transfer LittleEndianExplicit

hope the observation helps

ajgg

ConquestUpdate1416j