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knilch
3 Posts |
 Posted - Mar 26 2023 : 16:48:35
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Using ImageEN 11 I observed the following problem: After reading a DICOM file, uncompress it to raw and saving it back there are 2 fields missing in DICOM tags and one field is of a wrong value. The DicomTags Demo lists fields and values correct on the source file. The fields missing after saving are: "Rescale Slope" and "Rescale Intercept". The field "Bits Stored" is there but with a wrong value of 16, should be 12 (must be the field "High bit" [wich is 11 in the source file] + 1). For these reasons our CT scanner refused to import decompressed third party image data.
Maybe a fix could be offered?
Regards
knilch |
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xequte
38180 Posts |
Posted - Mar 26 2023 : 20:59:28
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Hi Knilch
Can you forward a sample file that shows the issue?
Nigel
Xequte Software
www.imageen.com
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knilch
3 Posts |
Posted - Mar 27 2023 : 02:15:29
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Please find attached the file DICOMS.zip. It includes 2 files: the original one and a second one generated by ImageEN (IMG-0001-00001_NEW.dcm). If you look at the end of the tags section, you find the 3 relevant differences (2 Tags missing [Rescale Intercept, Rescale Slope], 1 Tag [Bits stored] wrong value).
attach/knilch/202332721318_DICOMS.zip
684.77 KB |
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xequte
38180 Posts |
Posted - Mar 27 2023 : 17:58:55
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Thanks, we will investigate.
Nigel
Xequte Software
www.imageen.com
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xequte
38180 Posts |
Posted - Apr 06 2023 : 17:55:28
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Hi Knilch
When loading a DICOM image the pixel range is adjusted to display it correctly. This is controlled by:
https://www.imageen.com/help/TIOParams.DICOM_Range.html
By default, this is iedrAdjust which actually modifies the image (iedrSetBlackWhite is also available, but is not supported for saving).
In this situation the RescaleScope and RescaleIntercept tags are removed because they are no longer valid (i.e. will cause the modified image to display incorrectly when reloaded).
If you want to modify the tags without changing the image content, you can use InjectDICOMTags:
http://www.imageen.com/help/TImageEnIO.InjectDICOMTags.html
Nigel
Xequte Software
www.imageen.com
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knilch
3 Posts |
Posted - Apr 07 2023 : 02:30:39
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Hi,
thanks für investigating. Problem is: I HAVE to touch the pixel data because: Patients often bring discs with DICOM data from external examinations to out department where the image is compressed via JPEG Lossless. Our own archive however does only support uncompressed data and refused to import these external data. So what I try to achieve is decompress these images. This works with ImageEN. But as the resulting file misses the mentioned tags our archive again refuses to import the data.
At the moment I use software from GitHub that does the job and produces correct output in terms of decompression AND dicom tagging but due to internal considerations this won't work in the nearer future anymore...
Regards
knilch |
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DICOM Tags wrng/missing
