Bad Pixel Data? - DICOM

This is a discussion on Bad Pixel Data? - DICOM ; Need some help with a Pixel Data (7FE0,0010) value of 0. Is this a valid value for this element? Our implementation of DICOM C-STORE, which optionally converts the DICOM file to JPEG or TIF, crashes whenever it encounters a Pixel ...

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  1. Bad Pixel Data?

    Need some help with a Pixel Data (7FE0,0010) value of 0. Is this a
    valid value for this element? Our implementation of DICOM C-STORE,
    which optionally converts the DICOM file to JPEG or TIF, crashes
    whenever it encounters a Pixel Data of 0.

    Does anyone know 1) Can Pixel Data be zero? 2) If it can, why would it
    be zero?

    Here is a partial dump of the header of one of these files:

    0028,0000,Image Presentation Group Length=0
    0028,0002,Samples Per Pixel=1
    0028,0004,Photometric Interpretation=MONOCHROME2
    0028,0008,Number of Frames=1
    0028,0010,Rows=2016
    0028,0011,Columns=2448
    0028,0030,Pixel Spacing=0.079920 0.079130
    0028,0100,Bits Allocated=16
    0028,0101,Bits Stored=12
    0028,0102,High Bit=11
    0028,0103,Pixel Representation=0
    0028,1050,Window Center=2048
    0028,1051,Window Width=4095
    0040,0000,Group Length=0
    0040,1002,?=
    2020,0000,Group Length=0
    2020,0020,?=NORMAL
    7FE0,0000,Pixel Data Group Length=3161343
    7FE0,0010,Pixel Data=0
    FFFE,E000,Image Fragment [1494]=4
    FFFE,E000,Image Fragment [1506]=3161303
    FFFE,E0DD,Sequence Delimiter=0

    Thanks in advance!

    Chris


  2. Re: Bad Pixel Data?

    cmlasalle wrote:
    > Need some help with a Pixel Data (7FE0,0010) value of 0. Is this a
    > valid value for this element?


    On the one hand, "valid values" are numbers, and 0 is a number... On
    the other, it means that there's no pixel data, which kind of misses the
    point in an image! My guess is it's a bug somewhere, especially as your
    header dump indicates quite a sizeable chunk of file space dedicated to
    those non-existent pixels.

    Pete.
    --
    Peter Clinch Medical Physics IT Officer
    Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
    Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
    net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/

  3. Re: Bad Pixel Data?

    cmlasalle wrote:
    > Need some help with a Pixel Data (7FE0,0010) value of 0. Is this a
    > valid value for this element? Our implementation of DICOM C-STORE,
    > which optionally converts the DICOM file to JPEG or TIF, crashes
    > whenever it encounters a Pixel Data of 0.
    >
    > Does anyone know 1) Can Pixel Data be zero? 2) If it can, why would it
    > be zero?


    From the dump you have posted I would guess that the image is actually compressed (i.e., uses one
    of the so-called encapsulated transfer syntaxes). In this case, pixel data is not zero, but encoded
    very similar to a sequence with undefined length, with the (fffe,e000) attributes containing
    first an offset table and then fragments of compressed bitstream data. All of this is explained,
    quite in detail, in part 5 of the standard.

    Regards,
    Marco Eichelberg
    OFFIS

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