[Insight-users] Dynamic Threshold Filter

[Christian Werner]

Thank you very much. It is remarkable what you are contributing to this 
mailing list. One could say: You ARE the mailing list! I found out that 
you actually are the author of the ITK book, so it seems you are THE man 
anyway... :) I really enjoy working with this Kitware open source software.

You may remember that I am working with Paraview and write VTK plugins 
that use ITK filters. However I found out that many of the image 
processing is also available in VTK, like this median and subtraction 
you mentioned. It seems that VTK and ITK has some intersection here. So 
I will stick to the VTK version whenever possible.

I had some difficulties when using ITK filters anyway: Volume data that 
comes back from ITK cannot be displayed as volume in VTK anymore:

Cannot volume render since no point (or cell) data available.

Despite everything works fine, I can only view the data in slices. This 
is unfortunate since I finally managed to integrate Gaetens Analysis 
functions, especially the RGB labeling (which requires many common 
Gaeten-functions) as a plugin. With my superb ImageBox that's possible 
for any image data by the way! :) To bad the result which I import back 
to VTK can only be viewed in slices.

I see that this is likely more of a VTK or Paraview issue, so don't 
bother. Actually I asked the VTK mailing list, but it seems that they do 
not have a Luis Ibanez there... I will try the Paraview mailing list now.


Best regards.
Christian



Luis Ibanez wrote:
> Hi Christian,
>
> You could do:
>
> 1) Pass the input image through the
>     MeanImageFilter (with your kernel size)
>
> 2) Subtract the outcome of (1) from the input
>     image by using the SubtractImageFilter
>
> 3) Threshold the output of (2) with the standard
>      BinaryThreshold image filter.
>
>
> Of course, you could also implement this filter
> by merging together the code of the Mean
> subtract and threshold filters (not in a pipeline,
> but as a single pass filter).
>
> If you take this last option, it will be great if you
> share the filter with the ITK community by posting
> the code as a paper to the Insight Journal   :-)
>
>       http://www.insight-journal.org
>
>
>    Regards,
>
>
>         Luis
>
>
> -------------------------------
> On Fri, Mar 5, 2010 at 1:24 PM, Christian Werner
> <christian.werner at rwth-aachen.de> wrote:
>   
>> Hello!
>>
>> I didn't get to find a dynamic threshold filter in ITK, is there such? It is
>> typically used to extract pixel/voxels who's value differ about a certain
>> threshold from the average of a neigborhood in a given distance (kernel
>> size).
>>
>> In contrast to the simple BinaryThresholdImageFilter it catches elements
>> that "stand out" from the neighborhood.
>>
>> Any suggestions?
>>
>>
>> Best regards,
>> Christian
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