Re: Convolution kernels

Posted by Robert Dougherty on Feb 26, 2009; 11:12pm
URL: http://imagej.273.s1.nabble.com/Convolution-kernels-tp3693561p3693566.html

Dave,

I can reproduce your results, but I have to enter 2 for the radius,  
which produces a 5x5 kernel.   Entering 1 gives a 3x3 kernel, and  
anything less than 1 gives an interesting 1x1.  I don't know how to  
get a 2x2 mean without a shift.  If a shift is OK, you could convolve  
with

1 1 0
1 1 0
0 0 0

Bob

On Feb 26, 2009, at 11:33 AM, David Knecht wrote:

> Hi BOb- To test, I took a 20x20 black image and put a single 255  
> white pixel in the middle.  Then I ran a 2x2 mean filter.  I would  
> have predicted that only the pixels surrounding the white pixel  
> would be affected since all the others are more than 2 pixels  
> away.  I got a pattern of values of 12 up to that is 5 pixels high  
> and wide.   Dave
>
>