[Insight-users] Help : Error Using Discrete Guassian Filter

[Luis Ibanez]

Hi Neha,

The DiscreteGaussianImageFilter is described in the
software guide in Section 5.5.1, pdf-pages 110 to 112.

This filter performs smoothing by convolving the
image with a Gaussian kernel. The filter takes
advantage of the separability of the Gaussian.

The Gaussian kernel is approximated to a level of
tolerance set by the user. The lower the tolerance,
the better is the approximation, but the larger in
size is the kernel.

The MaximumKernelSize imposes a limit to the number
of pixels in the kernel. You may want to use values
in the range of 5 to 10.  Figure 5.14 in the Software
Guide will make this clearer for you.  The maximum
kernel size should be consistent with the value set
for Sigma in the Gaussian.

GaussianVariance (the squared value of Sigma) should
normaly be in the range of 2 to 10. Note that this
particular filter is not taking the spacing into
account, so all values are measured in pixels.

This shouldn't be a problem, Since you are reading
your image from a PNG file, and png files do not
contain information about pixel spacing.


An example on the use of this filter is
available in

Insight/Examples/Filtering/DiscreteGaussianImageFilter.cxx

This is exactly the same code illustrated in the
software guide.


Please let us know if you have further questions.


   Thanks


     Luis



-------------------

Neha D wrote:
> Hi All,
> 
> I am trying to use Discrete Gaussian Filter. I want to use filter on png 
> file of unsigned char. What value of maxKernelWidth should I use. With 
> values 0.2 , 0.1, I am getting error.
> 
> If anybody is using this filter, please let me know the appropriate 
> values for gaussianVariance ,  unsigned int maxKernelWidth .
> 
> Thanks,
> 
>  
>