Re: question about ultimate points

Posted by Michael Schmid on May 19, 2011; 4:28pm
URL: http://imagej.273.s1.nabble.com/question-about-ultimate-points-tp3684533p3684535.html

Hi Gabriel, Aryeh,

yes it is a bug in code contributed by me and I am working on how to  
solve it.
There is an easy fix, but I have to check whether it would slow down  
the code too much.

Michael
________________________________________________________________

On 19 May 2011, at 13:27, Gabriel Landini wrote:

> On Thursday 19 May 2011 11:53:23 you wrote:
>> I have an image in which binary->ultimate points (also biary-
>> >watershed)
>> causes some objects to disappear. I have a small example but it  
>> cannot
>> be posted.   I think you can download it from
>> http://www.megaupload.com/?d=8SCDE952
>
>
> Yes, it looks like a bug to me
>
>> It may be related to the fact that all pixels in the disappearing  
>> object
>> are neighbors to a boundary. However, note that a point object is  
>> left
>> intact.
>
> Not necessarily, you can have an ordered erosion of the blob which  
> has a
> preferential  asymmetry which leads to a point even in the case of  
> no-interior
> blobs like the example.
> If you add let's say a white disk somewhere then the blobs are  
> detected! So I
> think that the image is failing because just in the first iteration  
> the
> erosions get rid of the blob.
>
> I hope this helps to narrow down the problem.
>
> As an temporary measure you can skeletonise the image and then  
> apply the
> ulitimate points. That seems to work in your image.
>
> Cheers
> Gabriel