[Insight-users] Re: binary erosion

[Gaëtan Lehmann]

Hi Mauro,

I didn't have time to try your 3D image yet :-/

Le 29 nov. 07 à 01:48, mauro maiorca a écrit :

> On Nov 24, 2007 12:15 AM, mauro maiorca <mauromaiorca at gmail.com>  
> wrote:
>> Hi people,
>> I'm trying to perform erosion with itk, but unfortunately without any
>> luck. The strange thing is that there isn't any problem with  
>> dilation.
>
> problem solved adding:
>
> binaryErode->SetBackgroundValue( 0 );
> binaryErode->SetForegroundValue( 255 );
>
> to
>
>> binaryErode->SetKernel(  ball );
>> binaryErode->SetErodeValue( 255 );

This last line is equivalent to "binaryErode->SetForegroundValue 
( 255 );". The implementation is:

   void SetErodeValue(const InputPixelType& value)
     { this->SetForegroundValue( value ); }

So the only difference seems to be "binaryErode->SetBackgroundValue 
( 0 );", which should not explain the behavior you have.

What is the PixelType used in your code?

>
> hope it helps someone else: this thing was undocumented.
> It is incredibly slow, but probably switching to ITK 3.4 will solve  
> the problem.

It will help: binary erosion/dilation filters had a bug in ITK 3.2  
which was making them very slow, but wasn't affecting the result  
(that's why we didn't found the bug with the tests).
http://itk.org/cgi-bin/cvsweb.cgi/Code/BasicFilters/ 
itkBinaryMorphologyImageFilter.txx?root=Insight&r1=1.8&r2=1.9

> By the way, do you have any idea how to update just the
> erosion/dilation from 3.2 to 3.4 without reinstalling everything (it
> needs time, I want to postpone this)


just replace the file itkBinaryMorphologyImageFilter.txx in you  
installation tree by itkBinaryMorphologyImageFilter.txx from ITK 3.4.

Gaëtan


-- 
Gaëtan Lehmann
Biologie du Développement et de la Reproduction
INRA de Jouy-en-Josas (France)
tel: +33 1 34 65 29 66    fax: 01 34 65 29 09
http://voxel.jouy.inra.fr




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