[ITK] Otsu Filter for object/background separation

[Zein Salah]

well. is there a ready-made filter /function to automatically check if
the image has a bi-modal histogram?

On Wed, Nov 12, 2014 at 2:14 PM, Girish Mallya Udupi
<indianzeppelin at gmail.com> wrote:
> 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