Problem with Palette Color - DICOM

This is a discussion on Problem with Palette Color - DICOM ; Hi there, I am trying to convert a Segmented Palette to a regular Palette, taking the following file as input: http://cvs.creatis.insa-lyon.fr/view...S-ALOKA-16.dcm I am generating the following file: http://gdcm.sourceforge.net/thingies...OKA-16-LUT.dcm Using GDCM I can reread the image fine: http://gdcm.sourceforge.net/thingies...6-LUT.gdcm.png but using dcmtk ...

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Thread: Problem with Palette Color

  1. Problem with Palette Color

    Hi there,

    I am trying to convert a Segmented Palette to a regular Palette,
    taking the following file as input:

    http://cvs.creatis.insa-lyon.fr/view...S-ALOKA-16.dcm

    I am generating the following file:

    http://gdcm.sourceforge.net/thingies...OKA-16-LUT.dcm

    Using GDCM I can reread the image fine:

    http://gdcm.sourceforge.net/thingies...6-LUT.gdcm.png

    but using dcmtk I am getting some errors that I do not understand,

    WARNING: unsuitable value for 'BitsPerTableEntry' (16) ... assuming
    8 !
    WARNING: unsuitable value for 'BitsPerTableEntry' (16) ... assuming
    8 !


    and the image looks garbaged:

    http://gdcm.sourceforge.net/thingies...-LUT.dcmtk.png

    Thanks for any information.
    -Mathieu

  2. Re: Problem with Palette Color

    Mathieu,

    > but using dcmtk I am getting some errors that I do not understand,

    [...]
    > and the image looks garbaged:


    did you use the latest version of DCMTK (CVS snapshot)? Using the current
    version, I could convert the image using dcm2pnm without any warnings and
    with the expected result.

    Probably the following entry in the CHANGES file is related to this issue:

    === CUT ===

    **** Changes from 2007.03.16 (riesmeier)

    - Fixed problem with wrong interpretation of the palette descriptor in
    certain
    cases. Now the BitsPerTableEntry stored in the LUT descriptor is used by
    default. The previous behavior can be enabled using the ELM_CheckValue
    mode.
    Thanks to Ewald de Vries for the report.
    Affects: dcmimgle/libsrc/diluptab.cc

    === CUT ===

    The wrong interpretation in previous versions was the result of a
    workaround
    that is necessary for incorrectly encoded LUT descriptors ...

    Regards,
    Joerg

  3. Re: Problem with Palette Color

    On Sep 25, 1:34 pm, "Joerg Riesmeier" wrote:
    > Mathieu,
    >
    >
    >
    > > but using dcmtk I am getting some errors that I do not understand,

    > [...]
    > > and the image looks garbaged:

    >
    > did you use the latest version of DCMTK (CVS snapshot)? Using the current
    > version, I could convert the image using dcm2pnm without any warnings and
    > with the expected result.
    >
    > Probably the following entry in the CHANGES file is related to this issue:
    >
    > === CUT ===
    >
    > **** Changes from 2007.03.16 (riesmeier)
    >
    > - Fixed problem with wrong interpretation of the palette descriptor in
    > certain
    > cases. Now the BitsPerTableEntry stored in the LUT descriptor is used by
    > default. The previous behavior can be enabled using the ELM_CheckValue
    > mode.
    > Thanks to Ewald de Vries for the report.
    > Affects: dcmimgle/libsrc/diluptab.cc
    >
    > === CUT ===
    >
    > The wrong interpretation in previous versions was the result of a
    > workaround
    > that is necessary for incorrectly encoded LUT descriptors ...


    Thank you so much for report, I was getting ready to cut a new
    release !

    So just FYI TomoVision / PowerDicom / Irfanview and Dicomworks all
    fails to
    display properly the image. I will add that image to my gdcm DICOM
    conformance dataset.

    regards
    -Mathieu

  4. Re: Problem with Palette Color

    Joerg-san

    Thank you for your infomation.
    I have carefully read the infomation and I understand the bug in the
    dcmtk 3.5.4.
    By the way, there is one point I can't understand, it is the following
    context;

    > Now the BitsPerTableEntry stored in the LUT descriptor is used by
    > default. The previous behavior can be enabled using the ELM_CheckValue
    > mode.


    Please let me know what BitsPerTableEntry means, and what
    ELM_CheckValue mode means.
    I would appreciate it if you give me the answers of the above
    questions.

    Thanks,

    Maty

  5. Re: Problem with Palette Color

    > Please let me know what BitsPerTableEntry means, and what
    > ELM_CheckValue mode means.


    'BitsPerTableEntry' refers to the third value of the LUT Descriptor
    and ELM_CheckValue is explained in the source code documentation:

    /** bits per table entry modes.
    * Specifies whether the given value in the LUT descriptor is used.
    */
    enum EL_BitsPerTableEntry
    {
    /// use given value
    ELM_UseValue,
    /// ignore given value, use auto detection
    ELM_IgnoreValue,
    /// check whether given value is consistent with LUT data
    ELM_CheckValue
    };

    Btw, for further questions regarding DCMTK you should use the public
    discussion forum at http://forum.dcmtk.org/ .

    Regards,
    Joerg Riesmeier

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