[Insight-users] gaussian filter example

[Luis Ibanez]

Lydia,

ITK is N-Dimensional !!

These flexibility has been implemented using
templates in order to get the performance
advantage of compile time instantiations.

The GaussianFilter example however was writen
explicitly for 3D.

As you may have already noticed, the actual ITK
content of the example should be about 10% while
the rest of the code is dedicated to User
Interaction.

Loading a volume with only one slice will not
behave correctly as a 2D image because the filters
in the example will still try to smooth it along Z.

The recursive (IIR Infinite Impultional Response)
filters used for the Gaussians expect to find a
minimum of 9 pixels along the direction of the
filtering (because the order of the recursive
filter is 4 and it is applied first going forward
along a line and the going backbard).

It should be relatively easy to modify the example
to make it 2D.  It is mostly removing code  :-)
and replacing part of the GUI.

To convert the ITK part to 2D you just need to modify
lines 35 and 36 in liFilterConsoleBase.h

typedef   itk::Image< InputPixelType, 3 >   InputImageType;
typedef   itk::Image< PixelType, 3 >        ImageType;

replace the "3"'s by "2"'s and you are done !

All the filters are templated over the image type and
will automatically adjust the dimension at compile time.
So,... that's the easy part.

The slow part is the GUI, in which the 3D aspect is more
hard wired. I'll be glad to make these changes and create
a variant of the example if you are interested in have it.

Just let me know.


Thanks


Luis


==================================================







ycl lydia wrote:
> Stephen,
> thanks for your help but
> I tried with
> ElementSpacing = 1.48 1.48 1.48
> and
> ElementSpacing = 1.48 1.48 1 but it didn't work.
> 
> Maybe it works only with a volume of slices stored in the same raw file.
> 
> Lydia
> 
>> From: "Stephen R. Aylward" <aylward@unc.edu>
>> To: ycl lydia <ycllydia@hotmail.com>
>> CC: insight-users@public.kitware.com
>> Subject: Re: [Insight-users] gaussian filter example
>> Date: Mon, 15 Apr 2002 09:40:23 -0400
>>
>> Hi,
>>
>> I think the problem is the 0 in the z-dimension of element spacing.  Try
>> using
>> ElementSpacing = 1.48 1.48 1.48
>>
>> Also, MetaImage does support 2D images, but you're correct that the
>> Gaussian filter example won't.
>>
>> s
>>
>> ycl lydia wrote:
>>
>>> Hi,
>>> When I use the gaussian filter example with the brain web data, it works
>>> fine.
>>> I made my own metafile but using just one slice
>>> This is the file
>>> NDims = 3
>>> DimSize = 256 256 1
>>> ElementType = MET_USHORT
>>> ElementSpacing = 1.48 1.48 0
>>> ElementByteOrderMSB = False
>>> ElementDataFile = mr29.raw
>>>
>>> mr29 contains only one mri slice. These are the problems:
>>>
>>> 1.the image is loaded by the reader but is not displayed as it is. it's
>>> dark and without thresholding, i can't see waht 's inside
>>> 2. When I execute the filter, I get my screen becoming white.
>>> Did any one see this problem before?
>>> thank you for any hints
>>> Lydia
>>>
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>>
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> 
> 
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