[ITK-users] Too many label objects detected when only 3

[Girish Mallya Udupi]

That's correct.

Apart from looking at the number of label objects to confirm the
correctness of the labeling, it is also usually useful to convert the label
map to a label image and display/save that image (especially when the input
binary image is not coming from an internal binarization process).

On Fri, Apr 10, 2015 at 3:11 PM, Chr. Rossmanith <
cr at neuro.ma.uni-heidelberg.de> wrote:

>  Hi,
>
> your image isn't a true binary image but has some gray values close to 0
> (black) and some gray values close to 255 (white). I've converted it to a
> pure black-white PNG and now three regions should be detected. I guess JPG
> does some anti aliasing which introduces the additional grey values.
>
> Christina Rossmanith
>
>
>
>
> On 10.04.2015 14:32, Francisco Lopez de la Franca wrote:
>
>    Hi all.
>  I've just tested itk::BinaryImageToShapeLabelMapFilter with an B/W image
> (see attachment) containing only 3 object.
>
> I call the following methods:
>
> > binaryImageToShapeLabelMapFilter->ComputePerimeterOn();
> > binaryImageToShapeLabelMapFilter->SetInputForegroundValue(255);
> > binaryImageToShapeLabelMapFilter->SetOutputBackgroundValue(0);
> > binaryImageToShapeLabelMapFilter->Update();
>
> > LabelMapType::Pointer labelMap =
> binaryImageToShapeLabelMapFilter->GetOutput();
>
> > int nrOfLabelObjects = labelMap->GetNumberOfLabelObjects();
>
>  When I display the number of of label objects, the result is 246.
>
>  Does anybody know why this behaviour?
>
>  Thanks a lot.
>  My best regards.
>
>
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-- 
Regards,
Girish
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