LUTs

Hi!

Im very confused about LUT's in a dicom viewer environment.

Which LUT take the viewer for the image when:

- in the dicom image present a modality LUT
- no LUT in dicom image

And what is a presentation state? A external LUT defined from
the user?

Greets Funke

"Funke Kaiser" <fk@funkekaiser.de> wrote in message news:<ckmbr3$bfv$00$1@news.t-online.com>...[color=blue]
> Hi!
>
> Im very confused about LUT's in a dicom viewer environment.
>
> Which LUT take the viewer for the image when:
>
> - in the dicom image present a modality LUT
> - no LUT in dicom image
>
> And what is a presentation state? A external LUT defined from
> the user?
>
> Greets Funke[/color]

Funke

Try looking at Supplement 22
[url]ftp://medical.nema.org/medical/dicom/final/sup22_ft.pdf[/url]
it has all the LUT material all in one place instead of distributed
into the different DICOM Part Volumes

Take particular note of the drawing showing the pipeline/order of
precedence for Modality LUTs (used to produce the actual modality
output values) and Value Of Interest LUTs (used to modify the modality
output values emphasize or de-emphasize certain values when the image
is displayed or printed).

Yes, a presentation state is a standalone object, separate from the
image which can contain, among other things, LUTs where a user or
other device has defined a LUT which records the Value Of Interest
used to display the image. Calling it "standalone" is probably a
misnomer here since, although it is a separate object from the image,
the object has links specifying the image or images to which it
applies and therefore really cannot "stand alone" from those images.

I would strongly suggest not looking at Sup 22, or any of the
supplements, but instead Annex N of Part 4, which describes
the grayscale pipeline from images (instead of print) in
great detail, and in particular addresses some of the
exception cases (e.g. XA and XRF). Softcopy and print differ
in a number of ways.

You must also read section C.11 of Part 3, which is devoted
to the encoding and interpretation of the various lookup tables,
and has numerous notes elaborating on specific examples.

David

Eric Goodall wrote:
[color=blue]
> "Funke Kaiser" <fk@funkekaiser.de> wrote in message news:<ckmbr3$bfv$00$1@news.t-online.com>...
>[color=green]
>>Hi!
>>
>>Im very confused about LUT's in a dicom viewer environment.
>>
>>Which LUT take the viewer for the image when:
>>
>>- in the dicom image present a modality LUT
>>- no LUT in dicom image
>>
>>And what is a presentation state? A external LUT defined from
>>the user?
>>
>>Greets Funke[/color]
>
>
> Funke
>
> Try looking at Supplement 22
> [url]ftp://medical.nema.org/medical/dicom/final/sup22_ft.pdf[/url]
> it has all the LUT material all in one place instead of distributed
> into the different DICOM Part Volumes
>
> Take particular note of the drawing showing the pipeline/order of
> precedence for Modality LUTs (used to produce the actual modality
> output values) and Value Of Interest LUTs (used to modify the modality
> output values emphasize or de-emphasize certain values when the image
> is displayed or printed).
>
> Yes, a presentation state is a standalone object, separate from the
> image which can contain, among other things, LUTs where a user or
> other device has defined a LUT which records the Value Of Interest
> used to display the image. Calling it "standalone" is probably a
> misnomer here since, although it is a separate object from the image,
> the object has links specifying the image or images to which it
> applies and therefore really cannot "stand alone" from those images.[/color]