[Insight-users] Smoothing Vector Images

[Tom Vercauteren]

Hi Andreas,

Gaussian filters should handle vector images natively:
http://www.itk.org/Bug/view.php?id=2106

If not, could you produce a test case and reopen or create a new bug report?

Thanks,
Tom

On Wed, Jun 16, 2010 at 18:40, Merrem, Andreas
<andreas.merrem at medma.uni-heidelberg.de> wrote:
> Hi,
>
> Yes, that was my idea too... unfortunately the discrete Gaussian filter is
> even 3 times slower than the recursive one.
> Anyway, thanks a lot,
>
> Andreas
>
>
>
> ________________________________
> Von: Sergio Vera [mailto:sergio.vera at alma3d.com]
> Gesendet: Mittwoch, 16. Juni 2010 17:10
> An: Merrem, Andreas
> Cc: Bill Lorensen; insight-users at itk.org
> Betreff: Re: [Insight-users] Smoothing Vector Images
>
> Hello
> Extracted from the itk doxygen documentation:
> As compared to itk::DiscreteGaussianImageFilter, this filter
> (RecursiveGaussianImageFilter) tends to be faster for large kernels, and it
> can take the derivative of the blurred image in one step.
> so if you are using smaller sigmas and hence, smaller Gaussians,
> DiscreteGaussianImageFilter may result in faster execution time.
> And now I'm speculating but my guess is that 1 second to perform
> 3x256x256x22 convolutions is not dramatically slow (it seems reasonable, as
> those represents more than 4 millions of convolution operations), but i
> don't know if it can be done much more faster.
>
>
> On Wed, Jun 16, 2010 at 3:41 PM, Merrem, Andreas
> <andreas.merrem at medma.uni-heidelberg.de> wrote:
>>
>> Hi Bill and Sergio,
>>
>> Thank you for your answers.
>>
>> I tried using nth element adaptors and the
>> VectorIndexSelectionCastImageFilter, but it doesn't make it faster, what
>> takes time is really the smoothing itself (as you already expected).
>>
>> Yes, I built both the itk library and the application in release mode. Do
>> you think a second is a reasonable amount of time for smoothing 3 image
>> volumes of size 256*256*22?
>>
>> If anyone knows a smoothing filter that does Gaussian smoothing and works
>> faster than the itk recursive filter (perhaps something in frequency space)
>> that would be a great help.
>>
>>
>>
>>
>>
>> -----Ursprüngliche Nachricht-----
>> Von: Bill Lorensen [mailto:bill.lorensen at gmail.com]
>> Gesendet: Dienstag, 15. Juni 2010 20:12
>> An: Merrem, Andreas
>> Cc: Luis Ibanez; insight-users at itk.org
>> Betreff: Re: [Insight-users] Smoothing Vector Images
>>
>> First question: are you building ITK and your app with Release?
>>
>> On Tue, Jun 15, 2010 at 11:34 AM, Merrem, Andreas
>> <andreas.merrem at medma.uni-heidelberg.de> wrote:
>> > Hi Luis, hi everyone,
>> >
>> > I am trying to smooth 3D image volumes of size 256 * 256 * 22 pixels,
>> > in which each pixel contains a 3 dimensional itk::CovariantVector. The
>> > vector components should be smoothed independently over the whole
>> > volume. My current solution is to first copy the 3 vector components
>> > in each pixel into
>> > 3 separate images with pixel type float, then use the
>> > itk::RecursiveGaussianImageFilter for smoothing on all 3 images, and
>> > finally copy the pixel values of the smoothed images back into the
>> > covariant vector image.
>> >
>> > My problem is that this procedure takes about one second. As a part of
>> > a registration program, this leads to extremely slow registration
>> > (about 10 minutes for one 256*256*22 dicom volume). Is there a way to
>> > use less memory by avoiding the copying, or do you know a different,
>> > faster technique of applying a Gaussian filter?
>> >
>> > Thanks a lot,
>> >
>> > Andreas
>> >
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>
>
> --
> Sergio Vera
>
> Alma IT Systems
> C/ Vilana, 4B, 4º 1ª
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>
> _____________________________________
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