[vtkusers] [vtk-developers] Bug in vtkImageMapToColors

[David Gobbi]

Hi Nicolas,

The GetScalarRange() method computes the scalar range of the first component.

 - David


On Fri, May 6, 2011 at 3:00 PM, Nicolas Rannou
<nicolas_rannou at hms.harvard.edu> wrote:
> Hello,
>
> I'm experiencing a strange behavior in VTK which might be a bug.
> It took me a while to locate the issue:
>
> if I create a LUT with a NULL red component:
>   iRed = 0;
>   iGreen = 255;
>   iBlue = 255;
>   iAlpha = 255;
>   double iRange[2] = {0, 255};
>
>   vtkSmartPointer<vtkLookupTable> lut =
>       vtkSmartPointer<vtkLookupTable>::New();
>   double* HSV = vtkMath::RGBToHSV(iRed,iGreen,iBlue);
>   lut->SetAlpha(iAlpha);
>   lut->SetHueRange(HSV[0], HSV[0]);
>   lut->SetSaturationRange(1, 1);
>   lut->SetValueRange(0, 1);
>   lut->SetRange(iRange);
>   lut->Build();
>
> I color my image with this LUT:
>
>   vtkSmartPointer<vtkImageMapToColors> coloredImage =
>       vtkSmartPointer<vtkImageMapToColors>::New();
>   coloredImage->SetLookupTable(iLUT);
>   coloredImage->SetInput( iImage );
>   coloredImage->PassAlphaToOutputOff();
>   coloredImage->SetOutputFormatToRGB();
>   coloredImage->Update();
>
> then:
>   double* range = coloredImage->GetOutput()->GetScalarRange();
> returns [0,0].
> then everything I do with this image is messed up...
>
> If iRed != 0, the scalar range of the "coloredImage" will be correct then my
> pipeline is working.
>
> Am I doing something wrong?
>
> Thanks,
>
> Nicolas