Presentation LUT

Hello,

I'm using  LeadTools 15 C#.
While opening  a Dicom Dataset wa can apply automaticly the Modality LUT, teh VoiLUT.
But is it possible to Get the Presentaion Lut, and apply it to the image ?

Thank you.

You can request the Print SCP to create a Presentation LUT SOP Instance using the CreatePresentationLut Method.

Hello,
i think my question was not clear.

I'm developping a Print SCP. When i receive a dicom data set from Print SCU containing a presentation LUT :
 - how can i do to get the presentation Lut Data?
 - then how can i do to apply this presentation Lut to a raster image?

thanks.

To get the presentation LUT data, you need to:
1. Get the tag for the Presentation LUT Sequence.  Beneath that will be the LUT Data tag (there can be multiple instances of this tag, so that's why he needs to get the sequence first).
Details about the Presentation LUT module can be found in Part 3 section C.11.4 of the DICOM specifications.

2. For setting the LUT, you should create an array of RasterColors according to the rules and data you get from the Dataset and then set it with RasterImage.SetLookupTable method.

Hello,

Thanks for your answer.

I tried two manners to apply the Lut Sequence on the image.

- First one, using RasterImage.SetLookupTable

- Second one using RasterImage.WindowLevel(RasterImage.LowBit, RasterImage.HighBit, Lut,
RasterWindowLevelMode.Paint); where Lut is an Array of RasterColor[].

It gives me exactly the same result. But It seems to be wrong.

You will find in the Attachment a Dicom image, with a Dicom file containing the Lut
Sequence and the Jpg result. Can you tell if you obtain the same result?

Here is the Code :

private RasterImage OpenDataset(string file)
{
RasterImage image = null;
DicomElement element = null;
int bitmapCount = 0;

ds.Load(@"C:\HG_49774e3c651ac7c5.dcm", DicomDataSetLoadFlags.None);
element =
ds.FindFirstElement(null, DicomTagType.PixelData, true);
if (element != null)
{

bitmapCount = ds.GetImageCount(element);
if (bitmapCount > 0)
{
if (bitmapCount == 1)
{


if (element != null)

{

image = ds.GetImage(element, 0, 0, RasterByteOrder.Rgb,
DicomGetImageFlags.AutoApplyVoiLut |

DicomGetImageFlags.AutoApplyModalityLut
|

DicomGetImageFlags.AutoLoadOverlays |

DicomGetImageFlags.None);

}
}
}
}


StringCollection LutData = null;
DicomDataSet dsLut = new
DicomDataSet();
dsLut.Load(@"C:\SP_49774e3c651ac7c5.dcm", DicomDataSetLoadFlags.None);
if (dsLut != null)
{
if (Utils.IsTagPresent(dsLut,
DicomTagType.PresentationLutContentSequence))
{
RasterColor[] Lut = null;
if (Utils.IsTagPresent(dsLut,
DicomTagType.PresentationLutSequence))
{

string LutExplanation = Utils.GetStringValue(dsLut, DicomTagType.LutExplanation);

StringCollection LutDescriptor = Utils.GetStringValues(dsLut, DicomTagType.LutDescriptor);

LutData = Utils.GetStringValues(dsLut,
DicomTagType.LutData);

Lut = new RasterColor[LutData.Count
* 3];

for (int
i = 0; i < LutData.Count; i++)

{

Lut.SetValue((object)(new RasterColor(Convert.ToInt32(LutData[i]), Convert.ToInt32(LutData[i]), Convert.ToInt32(LutData[i]))), i);

}
}
if (image != null
&& Lut != null && Lut.Length
> 0)
{

//Methode 1 -------------------------

//image.SetLookupTable(Lut);


//Methode 2 -------------------------

//image.WindowLevel(image.LowBit,
image.HighBit, Lut, RasterWindowLevelMode.Paint);
}
}
}
return
image;
}


thanks.

Edited by moderator Thursday, November 3, 2016 12:48:21 PM(UTC)  | Reason: Not specified

I have noticed two things in your code:
1. You are creating a LUT that is 4096*3. You should change the length to 4096 instead of multiplying it by three.
2. You are not interpolating the values of the LUT into gray values. Windows can only display 256 shades of gray, which is why window leveling was created in the first place.
Since there are more than 256 intensity values in his image, you need to interpolate the values into grayscale values. When you fill the LUT, divide by 16 to convert the values from the range of 12 bit to the 8-bit.

Thanks a lot.
It works very well.
Bye

Hello, I now, can apply the presentation lut to the image.
But I seem to do it not right.
Here I let you a LUT.zip file, with a dicom file, a lut dicom file, and the preview of what result we have when we apply that lut to the image.

Every time we apply the LUT to the dicom image it gives different results.
Can you look at that please, and tell me what I do wrong?

Thank you
PS: the function I use to apply the LUT is "SetLookupTable".

What is the build number (version info) of the 'Leadtools.dll' and 'Leadtools.Dicom.dll'?
Does this happen with all files or only specific ones (like the one attached)?
Also, are you using the same project and code logic that we were working on the previous posts? If you modified anything, please send me updated code.

The version of Leadtools.dll and Leadtools.Dicom.dll is the 15.
The logic is the same, I get the Lut table, if it's one of a size of 4096 I reduce it to a 256 one.
And then "Image.SetLookupTable(Lut);"

So what could be the problem?

And it occurs with all the files.

I suggest that you first try this issue with the latest patches.
The DLL build number (version history) can be obtained when you right-click the DLL and choose properties (see attached image). If the build number that you have of the Leadtools.Dicom.dll is older than 15.0.1.23, contact support@leadtools.com and provide your serial number to obtain the latest patches.
If this build number you have, let me know.

Attached image

Yes, I have a version number : 15.0.1.7, could it really be the problem?
Thank you.

This issue might be solved using the latest patches, please send your serial number to support@leadtools.com and mention this post to obtain the latest patches.

That's already done, I have the lastest patches, and there is exactly the same problem.

I don't know what I'm doing wrong...

I have the version 15.0.1.23, and it's the same problem.

I have checked this at my side and the line:
Utils.IsTagPresent(dsLut, DicomTagType.PresentationLutContentSequence)
uses incorrect tag. Instead of PresentationLutContentSequence, the item that exists in the data set is actually PresentationLutSequence

Also, the LUT contains 256 entries, which is not a valid LUT for use with 12 or 16-bit grayscale images.