JPEG Lossy Identification Question - DICOM

This is a discussion on JPEG Lossy Identification Question - DICOM ; Hello, I've been noticing that some vendors are not providing the attribute (0028,2110) at all which would identify that Lossy Compression was used on the pixel data in the case where the transfer syntax used was a JPEG Lossy based ...

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Thread: JPEG Lossy Identification Question

  1. JPEG Lossy Identification Question

    Hello,

    I've been noticing that some vendors are not providing the attribute
    (0028,2110) at all which would identify that Lossy Compression was used
    on the pixel data in the case where the transfer syntax used was a JPEG
    Lossy based transfer syntax.

    If I understand the DICOM standard correctly, if a JPEG Lossy transfer
    syntax of any flavor is used then the attribute should be present and
    populated with "01". I did see notes that its Type 3 under the general
    description of the attribute for backward compatibility however in some
    specific IOD's there are modules that state its a 1C. So for those
    cases I'd expect to see a "01" in that attribute.

    If my understanding above is correct, would it be safe to assume that
    even in the case where the vendor didnt provide the attribute
    (0028,2110) but they did use a Lossy transfer syntax then the pixel
    data is Lossy? Therefore, during image review of the object a Lossy
    icon could be displayed to reflect this assumption? After all, a Lossy
    transfer syntax is lossy in itself right? (no critical need for the tag
    to identify Lossy in this particular case, but the tag becomes extra
    useful during transfer syntax conversions - to ILE or ELE from Lossy
    for example)

    Thanks!

    Homer


  2. Re: JPEG Lossy Identification Question


    Homer wrote:
    .....
    > If my understanding above is correct, would it be safe to assume that
    > even in the case where the vendor didnt provide the attribute
    > (0028,2110) but they did use a Lossy transfer syntax then the pixel
    > data is Lossy? Therefore, during image review of the object a Lossy
    > icon could be displayed to reflect this assumption? After all, a Lossy
    > transfer syntax is lossy in itself right? (no critical need for the tag
    > to identify Lossy in this particular case, but the tag becomes extra
    > useful during transfer syntax conversions - to ILE or ELE from Lossy
    > for example)


    Anytime the image transfer syntax is one of the lossy syntaxes, one
    would expect the attribute (0028,2110) to indicate lossy compression.
    If (0028,2110) is not present or set, yes it would be advisable to add
    it or otherwise indicate the image had been lossy compressed when it is
    rendered.

    The (0028,2110) attribute is there to cover the cases where the image
    may have been originally transmitted into a system via a lossy transfer
    syntax but later is transmitted from that system to another (e.g. a
    workstation retrieving it from a PACS) using a non-lossy transfer
    syntax. Attribute (0028,2110) serves as a flag to the receiving system
    saying "even though this instance pixel data is not being transmitted
    in a lossy compressed syntax, it has been subjected to lossy
    compression in its lifetime/path to your system" --implying you should
    display an indication of lossy compression when rendering the pixel
    data.

    Some other indicators coded into the image: most vendors will insert
    text into the Derivation Description (0028,2111) which states the image
    data has been subjected to lossy compression. The standard recommends
    this text include some estimate of the compression ratio applied to the
    image data. You'll note that most DICOM display software will show the
    content of (0028,2111) when an image is rendered even if the image data
    is not compressed. Usually it is not something that can be toggled off.
    This can actually be kind of annoying because some CR vendors include
    the CR processing algorithm parameters into (0028,2111).

    Also (0028,2114) can indicate the specific lossy compression algorithm
    applied to the data: Defined terms for this attribute are ISO_10918_1
    (for JPEG Lossy Compression) ISO_14495_1( for JPEG-LS Near-lossless
    Compression);
    ISO_15444_1 (for JPEG 2000 Irreversible Compression); and ISO_13818_2
    (for MPEG2 Compression)

    All the above is a paraphrase from 2006 Part 3, section C.7.6.1.1.5


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