[Dcmlib] DICOM Overlay sample

[Jean-Pierre Roux]

Saket Kulkarni wrote:
> Hi Jean-Pierre,
>   

Hi, Saket.

Please send the mails to
dcmlib at creatis.insa-lyon.fr
so the mailing list keeps a track of the questions (and the answers).
> I tried to open the DICOM image with overlay information using Sante /
> DicomWorks / ImageJ / MIPAV viewers. However I am not able to view the
> overlay data which is stored in the overlay tag (6000,3000). Please
> correct me if I am wrong, but once I have the data populated in that
> respective tag, a viewer which has the capability to read that tag
> should show the corresponding overlay data on the image. Please let me
> know where I could be wrong.
>   

This is not so easy :
they are 2 different ways to store the overlay data :

-> in the Data Elements 60xx|3000, each *bit* corresponds to a *byte* of 
the overlay image :
bit=0 -> byte=0000
bit=1 -> byte=1111

-> in the Pixel Data Element (7fe0|0010) the 'unused bits' are use to 
store overlays.
(unused : e.g. :  BitsStored=12, BitsAllocated=16, HightBit=11  --> 
unused bits : 12, 13, 14, 15)
in this case, DicomWorks display *always* the overlays.

in the first case, DicomWorks  *never* display  the overlays.

Have a look, in gdcm, within  the "Example" directory, at :
exExtractOverlaysACR.cxx
exExtractOverlaysDCM.cxx

(both read the image+overlays, and create as many files as they found 
'overlays')

HTH
Jean-Pierre



> Thanks again for all the help.
> Regards,
> -Saket
>
> On 10/29/07, Jean-Pierre Roux <jpr at creatis.insa-lyon.fr> wrote:
> Saket Kulkarni wrote:
>   
>> Hi, Saket.
>> Sorry for being late !
>> Here is the only image with overlays I've got in my collection :
>> MR-SIEMENS-DICOM-WithOverlays.dcm
>> a comment about the content :
>> MR-SIEMENS-DICOM-WithOverlays.README.txt
>> and a image with only the overlays :
>> MR-SIEMENS-DICOM-WithOverlays-extracted-overlays.dcm
>>
>> --> I just received an other one :
>> XA_GE_JPEG_02_with_Overlays.dcm
>>
>> HTH
>>
>> Jean-Pierre
>>     
>>> Hi Jean-Pierre,
>>> Could you please send me across any sample DICOM image with overlay
>>> tag populated. I need to understand how overlay information can
>>> populated in respective tags. You help would be highly appreciated.
>>> Thanks,
>>> -Saket
>>>
>>>
>>>       
>> Standard ACR-NEMA/DICOM fashion to store overlays :
>>
>> In a byte, 8 pixels are concerned (Overlay Bits Allocated = [1] )
>> Overlay Data length = 29282 (Overlay Rows * Overlay Columns)/8
>>
>> D 6000|0010 lg :        x(2)        2 [US]               [Overlay Rows] [484]
>> D 6000|0011 lg :        x(2)        2 [US]            [Overlay Columns] [484]
>> D 6000|0015 lg :        x(2)        2 [IS][Number of Frames in Overlay] [1 ]
>> D 6000|0022 lg :       x(1e)       30 [LO]        [Overlay Description] [Siemens MedCom Object Graphics]
>> D 6000|0040 lg :        x(2)        2 [CS]               [Overlay Type] [G ]
>> D 6000|0050 lg :        x(4)        4 [SS]             [Overlay Origin] [11]
>> D 6000|0051 lg :        x(2)        2 [US]         [Image Frame Origin] [1]
>> D 6000|0100 lg :        x(2)        2 [US]     [Overlay Bits Allocated] [1]
>> D 6000|0102 lg :        x(2)        2 [US]       [Overlay Bit Position] [0]
>> D 6000|3000 lg :     x(7262)    29282 [OW]               [Overlay Data] [gdcm::NotLoaded]
>>
>> Get the Data, expand them !
>> Hope there is never some oddities in Number of Frames in Overlay,
>>    Overlay Origin,Overlay Bit Position, etc .
>>
>>
>>     
>
>