Re: Variance Filter question

Posted by Michael Schmid on
URL: http://imagej.273.s1.nabble.com/Variance-Filter-question-tp3688151p3688152.html

On 27 May 2010, at 17:56, NatashaW wrote:

> Dear all,
>
> Could someone tell me how does variance filter work and which  
> article did
> they depend on in the implementation?
> It's not the usual one and I want to know how it detects the edge?
> I'm doing a summary about the functions that I'm using in my  
> research ..
>
> thank you so much for your help.

Hi Natasha,

it simply calculates the variance,
   http://en.wikipedia.org/wiki/Variance
of the values inside a region. The size of the region is given by the  
radius; see Process>Filter>Show Circular Masks.

I don't see what should be unusual about it - maybe except that  
clipping of large values may occur if you don't use float (32-bit) data.

Michael