How to turn off interpolation for discrete label segmentation image?

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Thanks for the reply!

Just want to confirm that the Nearest Neighbor Interpolation is not taking average of the neighboring voxels, right? I’m asking because now I suspect the issue might be caused by the incorrect interpolation in the downsampling from the upstream data pipeline (not vtk-js related).

Here’s my lut configuration. The original segmentation should only have label 4. But now 1, 2, 3, are also showing up at the border.

image

const seg_lut = vtkColorTransferFunction.newInstance();
seg_lut.setIndexedLookup(true);
seg_lut.setMappingRange(0, 4);
seg_lut.addRGBPoint(0, 0, 0, 0);
seg_lut.addRGBPoint(1, 1, 0, 0);
seg_lut.addRGBPoint(2, 0, 1, 0);
seg_lut.addRGBPoint(3, 0, 0, 1);
seg_lut.addRGBPoint(4, 1, 0.87, 0.74);

seg_actor.getProperty().setRGBTransferFunction(0, seg_lut);
seg_actor.getProperty().setColorLevel(2);
seg_actor.getProperty().setColorWindow(4);

const ofun = vtkPiecewiseFunction.newInstance();
ofun.addPoint(0, 0);
ofun.addPoint(1, 0.8);

seg_actor.getProperty().setScalarOpacity(ofun);
seg_actor.getProperty().setInterpolationTypeToNearest();