AW: [Insight-users] slice-wise running of filters

[Luis Ibanez]

Hi Zein,

I would discourage you from doing an slice
by slice approach for processing the 3D image.

Doing a single slice processing may be reasonable
as a way of providing rapid feedback for a user
in a GUI.

Is your volume strongly anisotropic ?
That is, is the Z spacing much larger than the
X and Y spacings ?

If this is the case, you can probably justify
to do 2D processing just because the slices
will be pretty uncorrelated anyways.


Otherwise, processing the whole volume in a 2D
slice basis will give you inconsistent results.

Filters like Smoothing, Erosion, Dilation,...
use neighborhood information in ND.
Running them in a 2D slice mode will result
in decorrelated results on the slices of the
output volume.

If performance is an issue, you may want to
consider other options as well.


   Luis



------------------------------------------
salah wrote:
> Luis,
> 
> I did not mean applying a filter on a single 
> slice form the image. what I mean is to apply
> the filter on EACH slices of the image as a 2D
> image. Of course, the result will not be the
> same as applying the filter on the 3D image 
> (for example, a region growing filter), but the
> result could be acceptable for filters such as 
> smoothing, dilation, erosion, ...
> 
> This could be done by having a loop that extract
> slices, apply filters to them as 2D images. But 
> I think, the time I hope to save will doubly spent
> in the many slice-extractions that are done. 
> 
> I hope the idea is more clear now.
> 
> Thanks,
> Zein 
> 
> 
> -----Ursprüngliche Nachricht-----
> Von: Luis Ibanez [mailto:luis . ibanez at kitware . com]
> Gesendet: Dienstag, 17. Juni 2003 15:32
> An: salah
> Cc: ITK Users (E-Mail)
> Betreff: Re: [Insight-users] slice-wise running of filters
> 
> 
> 
> Hi Zein,
> 
> The ExtractImageFilter is used for this purpose.
> 
> It takes your 3D volume, extracts a 2D slice and
> then you pass this slice to the actual filter.
> 
> NOTE that there is a difference between
> 
>    1) extract slice  + process 2D image
>    2) process 3D image + extract slice
> 
> In particular for all the filters that use neighbor
> information.
> 
> If you want to get 3D consistent results, you may
> want to use the SetRequestedRegion() feature in
> order to request a slice from the output.
> 
> 
> Regards,
> 
> 
>     Luis
> 
> 
> 
> --------------
> salah wrote:
> 
>>Hello all,
>>
>>I am wandering if there is some way to perform the
>>execution itk filters in a slice-wise fashion. This would 
>>much faster and could be quite sufficient for some
>>filters (smoothing filters, morphology filter, mean, median,
>>varience, ...).
>>
>>Does something like this already exist?
>>
>>Thanks,
>>Zein
>>
>>
>>->8<------------->8<------------->8<------------->8<------------->8<------------->8<-
>>Zein I. Salah 
>>University of Tübingen, WSI-GRIS, Sand 14, 72076 Tübingen 
>>Email: salah at gris . uni-tuebingen . de
>>Tel.: (07071) 29 75465 (GRIS),           Fax: (07071) 29 54 66
>>
>>_______________________________________________
>>Insight-users mailing list
>>Insight-users at www . itk . org
>>http://www . itk . org/mailman/listinfo/insight-users
>>
> 
> 
> 
> 
>