<br>Hi Eve,<br><br>These comments on the software guide were based on experiments that Paul <font size="-1">Yushkevich</font><br>ran several years ago comparing the multiple Gaussian smoothing filters available in ITK.<br>
<br>Unfortunately we made the mistake of not keeping the test as a permanent part of<br>the toolkit, so we will have to repeat that experiment in order to answer your question<br>properly.<br><br>My recollection is that a small kernel was in the range of "5x5x5",... but I may be wrong.
<br><br>This is the kind of experiment that could make a very interesting paper for the <br>Insight Journal: take the two filters and compare their computation time for <br>equivalent sigmas in images of different sizes.<br>
<br>You could setup this test by mixing the code of the two following examples:<br><br><ul><li>SmoothingRecursiveGaussianImageFilter.cxx</li><li>DiscreteGaussianImageFilter.cxx</li></ul><br>that you will find in the directory
<br><br> Insight/Examples/Filtering<br><br>In order to measure computation time you can use the class<br><br><ul><li>itkTimeProbesCollectorBase<br></li></ul><br>Please let us know if you find any problems when setting up
<br>this test.<br><br><br> Thanks,<br><br><br> Luis<br><br><br>------------------------------------------------------------------------------------<br><div><span class="gmail_quote">On 7/25/07, <b class="gmail_sendername">
Eve</b> <<a href="mailto:evelyn_heyes@homeworking.org">evelyn_heyes@homeworking.org</a>> wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<br>Hello,<br><br>According to ITK-Guide, "when the Gaussian kernel is small, the<br>itk::DiscreteGaussianImageFilter filter tends to run faster than<br>itk::RecursiveGaussianImageFilter". For a 200*20*200 volume, how small a
<br>kernel is consider "small"? i.e. what range is considered small? Also, what<br>are the (different) effects of "SetUseImageSpacing()" if the spacing between<br>slices is large vs. small?<br><br>Thanks,
<br>Eve<br><br>--<br>View this message in context: <a href="http://www.nabble.com/Discrete-vs.-RecursiveGaussianImageFilter--tf4148711.html#a11802231">http://www.nabble.com/Discrete-vs.-RecursiveGaussianImageFilter--tf4148711.html#a11802231
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