what is exactly OB OW VR for pixel data ? and how it is used ? - DICOM

This is a discussion on what is exactly OB OW VR for pixel data ? and how it is used ? - DICOM ; Hello, i have read : The Pixel Data Element (7FE0,0010) has a VR of OW or OB, depending on the negotiated Transfer Syntax. The only difference between OW and OB being that OB, a string of bytes, shall be unaffected ...

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Thread: what is exactly OB OW VR for pixel data ? and how it is used ?

  1. what is exactly OB OW VR for pixel data ? and how it is used ?

    Hello,

    i have read :

    The Pixel Data Element (7FE0,0010) has a VR of OW or OB, depending on
    the negotiated Transfer Syntax.
    The only difference between OW and OB being that OB, a string of
    bytes, shall be unaffected by Byte Ordering.

    i think information about ow ob are in PS 3.3 .. but i was be able to
    found informations about that.

    i would know when ow or ob must be used.
    i would know if during writing file received form remote pacs , an
    original file in OB is transformed into OW depending the writing
    transfert syntax. and if OW will stay in OW. the bit number is
    important or not (8 bit , 6 bit ) ?
    i would know if changing VR from OB to OW corrupt the pixeldata ??

    thanks

  2. Re: what is exactly OB OW VR for pixel data ? and how it is used?

    Hello Tom,

    it is rather straightforward:

    * in Encapsulated Syntaxes (compressed JPEG, for example), look at the
    Syntax Description in Part 5 PS3.5-2008 (Hint: most is OB ) )

    * in non encapsulated, non-compressed Syntaxes, look at the "Bits
    Allocated" (0028,0100).

    If you have 8 bit Image data, changing it to "OW" means, you read 2
    Pixels at once - this will result in rather psychedelic display.

    Hope this helps,


    Peter


    tom.marynowski@gmail.com wrote:
    > Hello,
    >
    > i have read :
    >
    > The Pixel Data Element (7FE0,0010) has a VR of OW or OB, depending on
    > the negotiated Transfer Syntax.
    > The only difference between OW and OB being that OB, a string of
    > bytes, shall be unaffected by Byte Ordering.
    >
    > i think information about ow ob are in PS 3.3 .. but i was be able to
    > found informations about that.
    >
    > i would know when ow or ob must be used.
    > i would know if during writing file received form remote pacs , an
    > original file in OB is transformed into OW depending the writing
    > transfert syntax. and if OW will stay in OW. the bit number is
    > important or not (8 bit , 6 bit ) ?
    > i would know if changing VR from OB to OW corrupt the pixeldata ??
    >
    > thanks


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