[Insight-users] Dicom Series Read Series Write: change in intensity values

["Eliana M. Vásquez Osorio"]

Hello itk-users,
I have a problem when writing (?) images series.  The intensity values 
change.
This is what I did:
- Read a series of dicom image into a volume
- Write the volume out as another series of dicom files in a different 
folder.
Since I do nothing in between (no filter is applied), I expected to get 
the same images after the writing process, but I found differences in 
the intensity values between the images.

My input images use 12 bits for storing image info. (Bits Stored=12, 
0028|0101 dicom tag).  The written image uses 16 bits.  I imagine that 
the intensity changes are related to this... but I don't get a clear 
idea how/why this changes the image that is produced.  Looking closely 
to the data, I found an offset of 1000 in the written images (compared 
to the original images).  Should I apply a filter to "correct" the 12 
bit to a 16 bit?  if so, which filter?  a casting filter?

Any idea or suggestion is welcome! :)
Thanks, Eliana