Re: Roi Enlarge (without merging) / ROI merging / Edges to ROI conversion

Posted by Michael Schmid on
URL: http://imagej.273.s1.nabble.com/Roi-Enlarge-without-merging-ROI-merging-Edges-to-ROI-conversion-tp3693456p3693463.html

Hi Ghislain,

one more remark:

There are a few points of difference between Binary>erode/dilate and  
Filters>minimum/maximum:

Erode (dilate) uses a square kernel areas, minimum (maximum) circular  
ones.
Often, especially for large radii (large iteration count), circular  
kernels are desireable. Dilate a small circular spot with several  
iterations to see the difference.

Minimum/maximum is a one-step operation, thus faster than erode/
dilate for large radii/large iteration count (the break-even depends  
on the image contents, it is around 3).

Erode has additional flexibility when handling edge objects (see  
"Count" in Binary Options)

Caveat:
- Minimum/maximum does not check whether you have a binary image.
- Minimum/maximum works on pixel values, irrespective or the LUT  
(inverted LUT or not) and "Black Background" setting in Binary options.

So my usual choice is erode/dilate for one or two pixels, minimum/
maximum for more.

Michael
________________________________________________________________

On 26 Nov 2008, at 20:34, Ghislain Bonamy wrote:

> Michael,
>
> Great solution, did not realize that the seeded-watershed was  
> hidden in
> "Find Maxima"! I followed the described strategy, but used dilate  
> (x times)
> instead of step (3).
>
> -convert edges to ROI... Works
>
> -Fusing ROIs: Thanks, I probably need to think a bit more about  
> that one. In
> brief I wanted to see if some of the startegy from definiens was  
> implemented
> or could easily be implmented.
>
> Ghislain
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