[Insight-users] are itkConnectedComponentImageFilter and itkBinaryDilateImageFilter

[Baoyun Li]

Dear Gaetan:

Claiming structur element as [3 3 1] seems to be a simple solution.

What I am wondering is how about if I only want to dilate or erod one voxel with slice? How to give teh structure elements in this case. Can I give structure elements as [1 1 0.33]?  Seem the way you suggested has to do dilation with slice with 3 voxel.

Is that true:
thanks

Baoyun




________________________________
From: Gaëtan Lehmann <gaetan.lehmann at jouy.inra.fr>
To: Baoyun Li <baoyun_li123 at yahoo.com>; Luis Ibanez <luis.ibanez at kitware.com>
Cc: ITK Users <insight-users at itk.org>
Sent: Mon, November 16, 2009 9:20:19 AM
Subject: Re: [Insight-users] are itkConnectedComponentImageFilter and itkBinaryDilateImageFilter


Hi,

For BinaryDilateImageFilter, it is possible to take the spacing into account when choosing the kernel size - the size on the third dimension should be three time smaller than on the two other ones - for example [3,3,1]. There is nothing to do for the ConnectedComponentImageFilter.

I'm not sure to understand how the spacing can have an impact on the performance of those filters - by definition, they are working on the neighbors of the pixels. Resampling the image shouldn't have much effect on the result, but will certainly have a quite bad effect on the execution time, and on the required memory!

Gaëtan


Le 15 nov. 09 à 16:48, Luis Ibanez a écrit :

> Hi Baoyun,
> 
> The two filters:
> 
> * itk::ConnectedComponentImageFilter    and
> * itk::BinaryDilateImageFilter
> 
> 
> Operate in Voxel (pixel) space.
> 
> They DO NOT take the image spacing into account.
> 
> 
> You may want to resample you image off spacings:
> 
>      0x6 x 0.6 x 2.5 mm
> 
> into an isotropic image with spacing
> 
>      0x x 0.6 x 0.6333
> 
> (e.g. splitting Z slices into three).
> 
> In this way, the operations of the Connectivity and Morphology
> filters will be closer to the intuitive expectations.
> 
> 
>      Regards,
> 
> 
>          Luis
> 
> 
> -----------------------
> On Fri, Nov 13, 2009 at 2:38 PM, Baoyun Li <baoyun_li123 at yahoo.com> wrote:
>> Dear All:
>> 
>> Can somebody tell me whetehr itkConnectedComponentImageFilter and
>> itkBinaryDilateImageFilter are operated on the physical space or voxel
>> space.
>> I have 0.6mmx0.6mmx2.5 mm ct data and want to do some morphorlogical
>> operation.
>> 
>> I think the performance will be affected if the morphorlogical operation is
>> done on voxel space.
>> 
>> So please guid me wheter those filters are operated on physical space? If
>> not, what should I do.
>> 
>> 
>> Thanks
>> 
>> Baoyun
>> 
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--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  http://www.itk.org
http://www.mandriva.org  http://www.bepo.fr


      
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