1. Forum
  2. Usenet
  3. COMP.PROTOCOLS.DICOM

  • Sequence enconding

    From =?UTF-8?Q?Valent=C3=AD_Montoya?=@21:1/5 to All on Wed Feb 3 05:47:23 2021
    Hi;

    I just want to ask about sequence DICOM element encoding.

    I know that exists two types of encoding a sequence(Explicit Length or Undefined Length).

    What is the best form? The DICOM standar recomends one of them? If yes, in which part of the standard can find that?


    Thank you.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From David Gobbi@21:1/5 to All on Wed Feb 3 08:45:41 2021
    The DICOM standard (PS 3.5 section 7.5.2) does not recommend either method over the other:

    The encoder of a Sequence of Items may choose either one of the two ways of encoding.
    Both ways of encoding shall be supported by decoders of the Sequence of Items.

    I don't know if one method is more popular, in my experience both methods are very common.

    Explicit length results in a slightly more compact file, but undefined length allows for sequences whose length is greater than the 32-bit limit imposed by the explicit length. In this regard, undefined length encoding is more robust.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From =?UTF-8?Q?Valent=C3=AD_Montoya?=@21:1/5 to All on Wed Feb 3 09:19:39 2021
    WoW!!

    Thanks a lot. I heared that undefined seqs lenght encoding is better than explicit and more secure.

    But, 32-bit limitation is something to keep in mind.


    Thank you David.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Mathieu Malaterre@21:1/5 to david...@gmail.com on Thu Feb 4 23:15:54 2021
    On Wednesday, February 3, 2021 at 5:45:44 PM UTC+1, david...@gmail.com wrote:
    The DICOM standard (PS 3.5 section 7.5.2) does not recommend either method over the other:

    The encoder of a Sequence of Items may choose either one of the two ways of encoding.
    Both ways of encoding shall be supported by decoders of the Sequence of Items.

    I don't know if one method is more popular, in my experience both methods are very common.

    Explicit length results in a slightly more compact file, but undefined length allows for sequences whose length is greater than the 32-bit limit imposed by the explicit length. In this regard, undefined length encoding is more robust.

    2. Explicit length in Implicit TS leads to CP-246,
    3. Undefined length SQ cannot be 'skipped', they need to be read data element after data element.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)