[vtkusers] Advice with setting LUT [vtkLookupTable] for FireIce (Hot/Cold)

[Marc Ferland]

On Tue, Apr 12, 2011 at 3:20 AM, Bc. Michal Srna <michal at srna.info> wrote:

> Hello,
>
> I am blending CT images with SPECT (nuclear medicine) images. I have found
> and tried some settings of vtkLookupTable (rainbow, hot...) for colormapping
> those SPECT images, but none of them suits my needs.
>
> I have one example of blending output of GE SPECT/low-dose CT Imaging
> system and it looks like that - http://goo.gl/8eDfH (third column of
> images). That is the colormapping I am aiming for.
>
> I tried to find some LUTs and it seems, that the closest is the FireIce
> (Hot/Cold) LUT, see the example here: http://goo.gl/KawPo
>
> I didn't find, how to set vtkLookupTable for creating LUT like that
> (SetHueRange,...). Could someone please help me, how to create LUT for
> colormapping like on that example (Hot/Cold)?
>
> My second question comes with transparency - I don't know, if it's possible
> to colormap just bones (not black parts of image) and black parts make
> totally transparent, so when blending it would looks like just bones were
> colormapped?
>
>
Hi,

I often use this one, which looks a little like your Matlab example:

   vtkSmartPointer<vtkColorTransferFunction> ctf =
      vtkSmartPointer<vtkColorTransferFunction>::New();
   ctf->AddRGBPoint(    0,   0,   0, 0.0);
   ctf->AddRGBPoint( 5567,   0,   0, 1.0);
   ctf->AddRGBPoint(11135,   0, 1.0, 1.0);
   ctf->AddRGBPoint(16376, 1.0, 1.0,   0);
   ctf->AddRGBPoint(21943, 1.0, 0.5,   0);
   ctf->AddRGBPoint(27184, 1.0,   0,   0);
   ctf->AddRGBPoint(32752, 0.5,   0,   0);

You should of course, modify the scalar range to suit your needs.

Enjoy!

Marc
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