Re: White particles

Posted by Gabriel Landini on May 21, 2008; 2:53pm
URL: http://imagej.273.s1.nabble.com/White-particles-tp3696155p3696159.html

On Wednesday 21 May 2008 15:28:55 Simon Roussel wrote:
> Your answer suggest that the particle analyser does take into account the
> black background option in Process/Binary, which is not the case.
> Analyse Particles always considers objects as black(=0).
> Otherwise, I would not have given this suggestion.

You are right that the particle analyser does not consider the background
setting. It does depend on the threshold setting.

If one wants the default to detect white particles, this should be a Threshold
(or better auto threshold) dialog setting, not a particle analysis one. That
way the detection is on the correct part of the greyscale. Does this make
sense?

Some programs do have a settings that define how all routines behave (so
dilation and erosion are consistent with the rest of thresholding and masking
operations). ImageJ is quite flexible on this, the thresholding is not, it is
hard wired to detect black blobs in autothreshold mode.

I do not think it is logical that the autothreshold will detect black objects
by default, but analyse white particles according to another setting. This
would work only if the image was thresholded (or made binary).

I think it would be better to have a threshold checkbox that controls what is
being segmented.

I hope this clarifies.

Cheers,
G.