DICOM File Without File meta information and Size preamble - DICOM

This is a discussion on DICOM File Without File meta information and Size preamble - DICOM ; Hi all, i found dicom data set of a CT scanner (sop class is 1.2.840.10008.5.1.4.1.1.2) and the files of this data set haven't got the file meta information (group 0002) and the size premble. In the standard P.S. 3-10 7 ...

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Thread: DICOM File Without File meta information and Size preamble

  1. DICOM File Without File meta information and Size preamble

    Hi all,
    i found dicom data set of a CT scanner (sop class is
    1.2.840.10008.5.1.4.1.1.2) and the files of this data set haven't got
    the file meta information (group 0002) and the size premble. In the
    standard P.S. 3-10
    7 DICOM File Format seems that a file Dicom must have the file meta
    information (group 0002) and the size premble, so my question is:
    - this file is in a valid format?
    -What can I do with a file like this (I'm developing an application to
    read Dicom File).

    Thanks in advantage for your help

    MM

  2. Re: DICOM File Without File meta information and Size preamble

    > i found dicom data set of a CT scanner and the files of this data set haven't got
    > the file meta information (group 0002) and the size premble. In the
    > standard P.S. 3-10
    > 7 DICOM File Format seems that a file Dicom must have the file meta
    > information (group 0002) and the size premble, so my question is:
    > - this file is in a valid format?
    > -What can I do with a file like this (I'm developing an application to
    > read Dicom File).


    Such files are not valid instances of the DICOM file format, but they
    are not unusual. Many (mostly older) DICOM toolkits/applications create
    such files. These files contain only the dataset without meta-header,
    which implies that the reader has to guess the Transfer Syntax, which
    cannot be deduced reliably from any part of the file.
    Therefore, readers typically assume that such files are
    a) Uncompressed
    b) Implicit VR Little Endian Transfer Syntax

    Some toolkits (such as DCMTK) contain heuristics to correctly guess
    byte order and explicit/implicit VR and thus in most cases also
    correctly read files in Explicit VR Little Endian or Explicit VR
    Big Endian transfer syntax.

    Best regards,
    Marco Eichelberg

  3. Re: DICOM File Without File meta information and Size preamble

    On Oct 15, 4:32 pm, Marco Eichelberg
    wrote:
    > > i found dicom data set of a CT scanner and the files of this data set haven't got
    > > the file meta information (group 0002) and the size premble. In the
    > > standard P.S. 3-10
    > > 7 DICOM File Format seems that a file Dicom must have the file meta
    > > information (group 0002) and the size premble, so my question is:
    > > - this file is in a valid format?
    > > -What can I do with a file like this (I'm developing an application to
    > > read Dicom File).

    >
    > Such files are not valid instances of the DICOM file format, but they
    > are not unusual. Many (mostly older) DICOM toolkits/applications create
    > such files. These files contain only the dataset without meta-header,
    > which implies that the reader has to guess the Transfer Syntax, which
    > cannot be deduced reliably from any part of the file.
    > Therefore, readers typically assume that such files are
    > a) Uncompressed
    > b) Implicit VR Little Endian Transfer Syntax
    >
    > Some toolkits (such as DCMTK) contain heuristics to correctly guess
    > byte order and explicit/implicit VR and thus in most cases also
    > correctly read files in Explicit VR Little Endian or Explicit VR
    > Big Endian transfer syntax.


    This heuristic (or a similar one) is explained here too:

    [2.2.3 Determining the Transfer Syntax of DICOM input Streams]
    http://www.dclunie.com/medical-image...tml/part2.html

    You should also realize that implementing those heuristics is
    extremely difficult, error prone, and you can forge properly crafted
    files to make almost any heuristic fails. Which means that for those
    files, you have to read it entirely to declare whether or not this is
    a "DICOM file".
    As a side note, try with the deflated transfer syntax too, I'll bet
    most (if not all) toolkits will reject them.

    And in case you are searching for exotics files, I recommend, gdcmData
    & gdcmConformanceTests

    * http://gdcm.sourceforge.net/wiki/ind...s_gdcmData_.3F
    * http://gdcm.sourceforge.net/wiki/ind...manceTests_.3F

    -Mathieu
    Ps: I have also seen DICOM files with a Preamble, no File Meta Header
    and then the DataSet.

  4. Re: DICOM File Without File meta information and Size preamble

    On 15 Ott, 16:46, Mathieu Malaterre
    wrote:
    > On Oct 15, 4:32 pm, Marco Eichelberg
    > wrote:
    >
    >
    >
    > > > i found dicom data set of a CT scanner and the files of this data set haven't got
    > > > the file meta information (group 0002) and the size premble. In the
    > > > standard P.S. 3-10
    > > > 7 DICOM File Format seems that a file Dicom must have the file meta
    > > > information (group 0002) and the size premble, so my question is:
    > > > - this file is in a valid format?
    > > > -What can I do with a file like this (I'm developing an application to
    > > > read Dicom File).

    >
    > > Such files are not valid instances of the DICOM file format, but they
    > > are not unusual. Many (mostly older) DICOM toolkits/applications create
    > > such files. These files contain only the dataset without meta-header,
    > > which implies that the reader has to guess the Transfer Syntax, which
    > > cannot be deduced reliably from any part of the file.
    > > Therefore, readers typically assume that such files are
    > > a) Uncompressed
    > > b) Implicit VR Little Endian Transfer Syntax

    >
    > > Some toolkits (such as DCMTK) contain heuristics to correctly guess
    > > byte order and explicit/implicit VR and thus in most cases also
    > > correctly read files in Explicit VR Little Endian or Explicit VR
    > > Big Endian transfer syntax.

    >
    > This heuristic (or a similar one) is explained here too:
    >
    > [2.2.3 Determining the Transfer Syntax of DICOM input Streams]http://www.dclunie.com/medical-image-faq/html/part2.html
    >
    > You should also realize that implementing those heuristics is
    > extremely difficult, error prone, and you can forge properly crafted
    > files to make almost any heuristic fails. Which means that for those
    > files, you have to read it entirely to declare whether or not this is
    > a "DICOM file".
    > As a side note, try with the deflated transfer syntax too, I'll bet
    > most (if not all) toolkits will reject them.
    >
    > And in case you are searching for exotics files, I recommend, gdcmData
    > & gdcmConformanceTests
    >
    > *http://gdcm.sourceforge.net/wiki/ind...tions#What_is_...
    > *http://gdcm.sourceforge.net/wiki/ind...tions#What_is_...
    >
    > -Mathieu
    > Ps: I have also seen DICOM files with a Preamble, no File Meta Header
    > and then the DataSet.


    Thank You all for your prompt answer, so that images are in Dicom
    standard but we to read them however.
    Thanks for the link but what is gdcm?

    Thanks again for your help.

    MM



  5. Re: DICOM File Without File meta information and Size preamble

    On Oct 16, 2:19 pm, vas...@yahoo.com wrote:
    > On 15 Ott, 16:46, Mathieu Malaterre
    > wrote:
    >
    >
    >
    > > On Oct 15, 4:32 pm, Marco Eichelberg
    > > wrote:

    >
    > > > > i found dicom data set of a CT scanner and the files of this data set haven't got
    > > > > the file meta information (group 0002) and the size premble. In the
    > > > > standard P.S. 3-10
    > > > > 7 DICOM File Format seems that a file Dicom must have the file meta
    > > > > information (group 0002) and the size premble, so my question is:
    > > > > - this file is in a valid format?
    > > > > -What can I do with a file like this (I'm developing an application to
    > > > > read Dicom File).

    >
    > > > Such files are not valid instances of the DICOM file format, but they
    > > > are not unusual. Many (mostly older) DICOM toolkits/applications create
    > > > such files. These files contain only the dataset without meta-header,
    > > > which implies that the reader has to guess the Transfer Syntax, which
    > > > cannot be deduced reliably from any part of the file.
    > > > Therefore, readers typically assume that such files are
    > > > a) Uncompressed
    > > > b) Implicit VR Little Endian Transfer Syntax

    >
    > > > Some toolkits (such as DCMTK) contain heuristics to correctly guess
    > > > byte order and explicit/implicit VR and thus in most cases also
    > > > correctly read files in Explicit VR Little Endian or Explicit VR
    > > > Big Endian transfer syntax.

    >
    > > This heuristic (or a similar one) is explained here too:

    >
    > > [2.2.3 Determining the Transfer Syntax of DICOM input Streams]http://www.dclunie.com/medical-image-faq/html/part2.html

    >
    > > You should also realize that implementing those heuristics is
    > > extremely difficult, error prone, and you can forge properly crafted
    > > files to make almost any heuristic fails. Which means that for those
    > > files, you have to read it entirely to declare whether or not this is
    > > a "DICOM file".
    > > As a side note, try with the deflated transfer syntax too, I'll bet
    > > most (if not all) toolkits will reject them.

    >
    > > And in case you are searching for exotics files, I recommend, gdcmData
    > > & gdcmConformanceTests

    >
    > > *http://gdcm.sourceforge.net/wiki/ind...tions#What_is_...
    > > *http://gdcm.sourceforge.net/wiki/ind...tions#What_is_...

    >
    > > -Mathieu
    > > Ps: I have also seen DICOM files with a Preamble, no File Meta Header
    > > and then the DataSet.

    >
    > Thank You all for your prompt answer, so that images are in Dicom
    > standard but we to read them however.
    > Thanks for the link but what is gdcm?


    you are kiddin', right ? You cannot possibly be serious ...

    Did you scroll to the top of the page I sent you ?

    http://gdcm.sourceforge.net/wiki/ind...hat_is_GDCM.3F

    -M

  6. Re: DICOM File Without File meta information and Size preamble

    On 16 Ott, 16:28, Mathieu Malaterre
    wrote:
    > On Oct 16, 2:19 pm, vas...@yahoo.com wrote:
    >
    >
    >
    > > On 15 Ott, 16:46, Mathieu Malaterre
    > > wrote:

    >
    > > > On Oct 15, 4:32 pm, Marco Eichelberg
    > > > wrote:

    >
    > > > > > i found dicom data set of a CT scanner and the files of this data set haven't got
    > > > > > the file meta information (group 0002) and the size premble. In the
    > > > > > standard P.S. 3-10
    > > > > > 7 DICOM File Format seems that a file Dicom must have the file meta
    > > > > > information (group 0002) and the size premble, so my question is:
    > > > > > - this file is in a valid format?
    > > > > > -What can I do with a file like this (I'm developing an application to
    > > > > > read Dicom File).

    >
    > > > > Such files are not valid instances of the DICOM file format, but they
    > > > > are not unusual. Many (mostly older) DICOM toolkits/applications create
    > > > > such files. These files contain only the dataset without meta-header,
    > > > > which implies that the reader has to guess the Transfer Syntax, which
    > > > > cannot be deduced reliably from any part of the file.
    > > > > Therefore, readers typically assume that such files are
    > > > > a) Uncompressed
    > > > > b) Implicit VR Little Endian Transfer Syntax

    >
    > > > > Some toolkits (such as DCMTK) contain heuristics to correctly guess
    > > > > byte order and explicit/implicit VR and thus in most cases also
    > > > > correctly read files in Explicit VR Little Endian or Explicit VR
    > > > > Big Endian transfer syntax.

    >
    > > > This heuristic (or a similar one) is explained here too:

    >
    > > > [2.2.3 Determining the Transfer Syntax of DICOM input Streams]http://www.dclunie.com/medical-image-faq/html/part2.html

    >
    > > > You should also realize that implementing those heuristics is
    > > > extremely difficult, error prone, and you can forge properly crafted
    > > > files to make almost any heuristic fails. Which means that for those
    > > > files, you have to read it entirely to declare whether or not this is
    > > > a "DICOM file".
    > > > As a side note, try with the deflated transfer syntax too, I'll bet
    > > > most (if not all) toolkits will reject them.

    >
    > > > And in case you are searching for exotics files, I recommend, gdcmData
    > > > & gdcmConformanceTests

    >
    > > > *http://gdcm.sourceforge.net/wiki/ind...tions#What_is_...
    > > > *http://gdcm.sourceforge.net/wiki/ind...tions#What_is_...

    >
    > > > -Mathieu
    > > > Ps: I have also seen DICOM files with a Preamble, no File Meta Header
    > > > and then the DataSet.

    >
    > > Thank You all for your prompt answer, so that images are in Dicom
    > > standard but we to read them however.
    > > Thanks for the link but what is gdcm?

    >
    > you are kiddin', right ? You cannot possibly be serious ...
    >
    > Did you scroll to the top of the page I sent you ?
    >
    > http://gdcm.sourceforge.net/wiki/ind...tions#What_is_...
    >
    > -M


    Really I don't know, it seems gdcm is Dicom library, but I don't
    understand how can I use it. Sorry for my not knowledge about it. I'm
    not so expert in Dicom, I studied the standard to implement some
    software to be compatible with Dicom 3.0 to export in Dicom format and
    to read Dicom format, nothing else....

    MM

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