[vtk-developers] Image filter to remap labels to new values

[David Gobbi]

On Wed, Mar 29, 2017 at 10:42 AM, David Thompson <david.thompson at kitware.com
> wrote:

> Hi David,
>
> > ...I'm planning to add a new image filter to VTK, and will name it
> something like vtkImageMapThroughLUT.  The operation of this filter will be
> as follows:
> >
> > - It will take, as input, any image that uses an integer scalar type
> > - The scalars will be mapped though a lookup table to generate the
> output image
> >
> > For the "lookup table" or (LUT), I was planning to use a plain-old
> vtkDataArray.  I cannot use vtkLookupTable as the LUT, since vtkLookupTable
> can only produce "unsigned char" output and is meant to be used for
> generating color data.
> >
> > My question to the list is as follows: is vtkDataArray the best object
> to use for storing such a LUT?
>
> You might consider vtkPiecewiseFunction (in Common/DataModel).
>
> > Also, is there already a class in the VTK geometry pipeline that allows
> labels to be remapped to new label values via a LUT?
>
> I don't know of any; what format are the labels in?
>

The "labels", in this case, are just scalar values.  The use case is images
that represent brain segmentations, where a pixel value of "0" represents
nothing, a pixel value of "1" represents one particular region of the
brain, a pixel value of "2" represents a different region of the brain,
etc.  Such images are commonly used in neuroscience imaging research, and
are often called "label images" or, depending on their use, "atlas images".

So we're talking about simply mapping integer scalar values through a LUT,
to get a new set of integer scalar values.

 - David
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