Analyze particles: what is the wand tool mode setting?

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Analyze particles: what is the wand tool mode setting?

Struk, Peter M. (GRC-RTI0)
ImageJ Users,

I am trying to understand which of the 3 Wand Tool modes (legacy, 4-connected, or 8-connected) are used in the "Analyze Particles" command.  Does anybody know?  Also, can this be changed while using "Analyze Particles"?  Finally, does anybody have a better description on how wand tool works in legacy mode  (docs say no neighbor is checked but how can that be)?

Pete


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Re: Analyze particles: what is the wand tool mode setting?

Michael Schmid
Hi Pete,

the modes '4-connected' and '8-connected' refer to the neighborhood.
4-connected means that all pixels of a particle recognized by the wand must be connected via pixel EDGES.  Each pixel shares edges with 4 neighboring pixels.
The 8-connected mode means that pixels may be connected via edges or CORNERS.  Each pixel shares edges or corners with 8 neighboring particles.

The 'legacy' mode tries to determine whether it should be '4-connected' or '8-connected', depending on whether it thinks that the user was trying to trace a 1-pixel-wide line (4-connected) or a thicker object (8-connected). Unfortunately, the result can be unpredictable.

4- and 8-connected modes always trace a thresholded are (if the image is thresholded) or an area having the same pixel values as the point where the user has clicked (values within the tolerance, if tolerance>0).  The legacy mode is somewhat unpredictable in this respect, it can either trace an area like the 4- or 8-connected mode or an inner hole (if there is an inner hole exactly at the right form the starting position).

In ImageJ 1.42 and before, only the 'legacy' mode was available, hence the name.

The Wand Tool options affect only the tool, not the "Analyze Particles". "Analyze Particles" is always 8-connnected. For 4-connected measurements, see the Paricles4_ plugins on Gabriel Landini's web page
  http://www.dentistry.bham.ac.uk/landinig/software/software.html

Also several binary commands (distance map, etc) and 'Find Maxima' are always 8-connected.

Michael
________________________________________________________________
On Apr 4, 2013, at 16:22, Struk, Peter M. (GRC-RTI0) wrote:

> ImageJ Users,
>
> I am trying to understand which of the 3 Wand Tool modes (legacy, 4-connected, or 8-connected) are used in the "Analyze Particles" command.  Does anybody know?  Also, can this be changed while using "Analyze Particles"?  Finally, does anybody have a better description on how wand tool works in legacy mode  (docs say no neighbor is checked but how can that be)?
>
> Pete

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