[Dcmlib] Re: some bugs with 'MONOCHROM1 ' and 'MONOCHROM2 '

[Jean-Pierre ROUX]

At 11:00 -0500 12/11/04, Mathieu Malaterre wrote:
>Jean-Pierre Roux wrote:
>>>Dennis,
>>>
>>>	I am really suspicious. I only know one image that had odd lenght, and
>>>it was an image written by an old gdcm version. Two options here:
>>>
>>
>>
>>--> Mathieu :
>>Actually, there is a lot of DICOM images with odd length for some fields
>>(not only old gdcm version written images ...)
>>Of course, it's a violation of DICOM rules, but who cares about DICOM
>>rules :-(
>
>JP,
>
>	Show me one DICOM in the baseLine that does not respect this 
>rule (except the theralys one and the broken GE 13 lenght).

Mathieu,

In the 'dcm dataset', there is no image (except the Theralys one) 
with odd lengths.
A few weeks ago I downloaded an image whose some lengths of elements 
belonging to a shadow group (0009) are odd, so I think we can find a 
lot of others, in the world ...
What I meant is that the commit you did corrects the length *and* the 
string, in order to avoid further troubles (great !), but PrintHeader 
displays the length (and the string) as they are after the 
correction, so we cannot see at a glance if the image does contain an 
oddity or not.

--------------

An other 'funny stuff' we never experienced is that Dicom norm says 
the "meta elements" (group 0002) must *always* be coded in little 
endian, and the remaining of the header must follow 'Transfert 
Syntax'.

In gdcm we have an heuristic to guest if the endianity of the image 
is equal to the endianity of the processor we're currently using, and 
we only check Transfert Syntax value for compression purpose, not for 
endianity purpose...

JPRx


>I think there is a confusion in between MONOCHROM1 that has 11 
>character and the string that carry it that is padded with a null 
>caracter (as specified in DICOM ref). I put a tons of assert 
>everywhere to make sure about this issue, and I had an issue only 
>with those two.
>
>Thanks,
>Mathieu

   Jean-Pierre ROUX
   UMR CNRS 5515-CREATIS
   Laboratoire de Radiologie Experimentale
   Hopital Cardiologique
   28 Avenue du Doyen LEPINE
   B.P. Lyon-Montchat
   69394 Lyon Cedex 03
 
   Tel      : (+33) 04 72 35 74 12
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   e-mail   : jpr at creatis.univ-lyon1.fr