Vtk-js: when I use InteractorStyleMPRSlice, how to set the windowLevel and windowCenter?

[zhirui1994]

I used the InteractorStyleMPRSlice class，but the image is not one I like， I want to set the win
dowLevel and windowCenter to change the color，but I don't know how to do it. can somenoe help me?

[agirault]

You should have a vtkImageSlice object which holds a vtkImageProperty object, on which you'll want to call colorWindow (window width really) and colorLevel (window level).

[floryst]

Sicne InteractorStyleMPRSlice renders a volume as a thin slab, you'll need to modify the vtkVolumeProperty (you can get this via vtkVolume.getProperty()). Since there is no window width/level property on volumes, you can get the same by setting the color transfer function mapping range. Below is some quick code on how to do this:

window = 255;
level = 127;

mappingRangeLower = level - window / 2.0;
mappingRangeUpper = level + window / 2.0;

volumeActor.getProperty().getRGBTransferFunction(0).setMappingRange(mappingRangeLower, mappingRangeUpper);

[zhirui1994]

@agirault @floryst Thanks very much！It's helped me.

[GreyFoxRU]

Please tell me what I'm doing wrong?
I get data through cornerstone by images, by values, and rendering through it looks very correct, but when transferring images to vtk, setting values ​​using codes 0028,1050 and 0028,1051, the picture drawn by vtk is drawn brightly.

"vtk.js": "^8.14.0"

For setting windowLevel I am using code:

        const window = 400; // cornerstone image.windowWidth = 400
        const center = 40; // cornerstone image.windowCenter = 40

        const mappingRangeLower = center - window / 2;
        const mappingRangeUpper = center + window / 2;

        volumeActor.getProperty()
          .getRGBTransferFunction(0)
          .setMappingRange(mappingRangeLower, mappingRangeUpper);

Updated vtk to version 14.5.0, graininess disappeared, but the problem with overlighting remained.

[neroooren]

@GreyFoxRU: maybe you should try convert image pixel value to CT value: 'Hu = pixel * slope + intercept', slop and interceptcan can get from dicom tag.