[vtkusers] scalar value to color mapping

[Dr. Jörg Seemann (V2T)]

Dear VTK-users,

I tried to map scalar image data to a color map.

Firstly, I defined a rainbow lookup table:

  vtkLookupTable *lut = vtkLookupTable::New();
    lut->SetTableRange (minimumResult1, maximumResult1);
    lut->SetHueRange (0.6667, 0.0);
    lut->SetSaturationRange (1.0, 1.0);
    lut->SetValueRange (1.0, 1.0);
    lut->SetAlphaRange (1.0, 1.0);
    lut->SetNumberOfColors (256);
    lut->Build();

Here minimumResult1 and maximumResult1 are the minimum and maximum of the
image data.

Next, I used the vtkImageMapToWindowLevelColors filter:

    vtkImageMapToWindowLevelColors *Colors =
vtkImageMapToWindowLevelColors::New();
    Colors->SetInput(resample->GetOutput());
    Colors->SetLookupTable(lut);
    Colors->SetWindow(maximumResult1-minimumResult1);
    Colors->SetLevel((maximumResult1-minimumResult1)/2);
    Colors->Update();

Finally, I used the vtkImageViewer to render the image.

    vtkImageViewer *viewer = vtkImageViewer::New();//window to visualisation
    viewer->SetInput(Colors->GetOutput());

    viewer->SetColorWindow (255.0);
    viewer->SetColorLevel (127.5);
    viewer->Render();

I expected that the data range would cover the whole color palette,
but I does nor work, if minimumResult1 is a negative (negative values are
missing using the
above code).

May somebody know how to set the parameter for the filters correctly?

Best regards,

Jörg