[ITK] Otsu Filter for object/background separation

[Girish Mallya Udupi]

Hi Zein,

As you might know, Otsu's method *assumes *that the histogram of the image
is bi-modal. i.e., there are two classes of pixels forming two peaks
separated by a valley.
All the method (and the corresponding ITK filter) does is calculate the
threshold which maximizes the inter-class variance and apply it on the
image.


On Wed, Nov 12, 2014 at 12:43 PM, Zein Salah <zeinsalah at gmail.com> wrote:

> Hello,
>
> I have been using the otsu filter for doing object-from-background
> separation. However, I noticed that the filter always comes out with an
> separation threshold, even if the image does NOT actually have a
> "reasonable" background, see the attached image, e.g..
>
> My question is: is it possible to control the filter in such a way that it
> only generate a threshold if there is really a background?
>
> Practically, I could, in a post-processing step,  do a decision weather
> the separation is feasible or not, e.g. computing the comparing the
> statistics of the two separated areas (average intensity, variance, etc.).
> But I thought the otsu filter already does such things internally, right?
> Is it possible to inquire such data from the filter?
>
> Any ideas would be welcome!!
>
> Much thanks,
>
> Zein
>
>
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-- 
Regards,
Girish
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