Why is Particle Analyzer 8-connected?

[Sidnei Paciornik]

Dear colleagues

I have found a few posts regarding the fact that ImageJ Particle Analyzer
is intrinsically 8-connected. I am also aware of Landini´s great set of
plugins that allow 8 or 4 connected pixels measurements. I am also aware
that DoWand can be either 4 and 8 connected, but that does not affect the
Analyse Particles function.

But the question is:
WHY is Particle Analyzer 8-connected? Is there any fundamental reason for
this choice? It seems to be an unreasonable restriction...

Thank you all!

Prof. Sidnei Paciornik
DEQM PUC-Rio
Brazil

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[Michael Schmid]

Hi Sidnei,

in ImageJ essentially everything is 8-connected, also all the Process>Binary commands, Find Maxima, flood filling, etc. So the Wand is an exception, not the Particle Analyzer.

Apart from the tradition, this also has the advantega of keeping it simple, not only the code but also the user interface. I may be wrong, but I guess that well above 50% of the users don't know the difference between 4-connected and 8-connected.

Michael
________________________________________________________________
On May 7, 2015, at 14:31, Sidnei Paciornik wrote:

> Dear colleagues
>
> I have found a few posts regarding the fact that ImageJ Particle Analyzer
> is intrinsically 8-connected. I am also aware of Landini´s great set of
> plugins that allow 8 or 4 connected pixels measurements. I am also aware
> that DoWand can be either 4 and 8 connected, but that does not affect the
> Analyse Particles function.
>
> But the question is:
> WHY is Particle Analyzer 8-connected? Is there any fundamental reason for
> this choice? It seems to be an unreasonable restriction...
>
> Thank you all!
>
> Prof. Sidnei Paciornik
> DEQM PUC-Rio
> Brazil
>
> --
> ImageJ mailing list: http://imagej.nih.gov/ij/list.html

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[Gabriel Landini]

On Thursday 07 May 2015 09:31:19 you wrote:
> But the question is:
> WHY is Particle Analyzer 8-connected? Is there any fundamental reason for
> this choice? It seems to be an unreasonable restriction...

By design, most probably. I do not think it is an unreasonable restriction. 4-
connected regions are difficult discern visually and also have overestimated
perimeters.

If you need the 4-connected you can use the Particles4 plugin.

Cheers
Gabriel

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