Thank you all!<br><br>The situation is : some connected pnts are forming one group to be one star; there're several stars which are not connected with each other. Any good suggestions?<br><br>Currently I tried kmeans (itkImageKmeansModelEstimator) to cluster them. It works but one problem is hard to find the right "k" number, since the total number of stars are unknown. I definitely will try what Kishore and Lynx suggested on Monday. <br>
<br><br>Regards,<br><br>Tao<br><br><div class="gmail_quote">On Sun, Nov 1, 2009 at 1:14 PM, Luis Ibanez <span dir="ltr"><<a href="mailto:luis.ibanez@kitware.com">luis.ibanez@kitware.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Hi Tao,<br>
<br>
Your problem looks very interesting.<br>
<br>
However,<br>
It wasn't clear for me, from the description in your email,<br>
whether the list of bright points are indeed pixels that are<br>
connected to each other and that form a single star or not.<br>
<br>
If they are connected, then, you can certainly use the<br>
filters that Kishore and Lynx suggested.<br>
<br>
However, if you are trying to define a given star by<br>
aggregating a set of bright pixels that are not<br>
connected, then you may have to pursue other<br>
techniques.<br>
<br>
Please let us know more details about the problem.<br>
<br>
(a screenshot of one of the image will be ideal...)<br>
<br>
<br>
Thanks<br>
<br>
<br>
Luis<br>
<br>
<br>
---------------------------------------------------------------<br>
<div><div></div><div class="h5">On Wed, Oct 28, 2009 at 12:56 PM, Tao Dai <<a href="mailto:uniquedai@gmail.com">uniquedai@gmail.com</a>> wrote:<br>
> Dear Luis and ITK list:<br>
><br>
> I am working on one project and trying to do some work like "finding<br>
> stars": Assuming there're lots of stars (difference size/brightness) in the<br>
> night sky, I wanna extract those stars and calculate areas and brightness<br>
> for each.<br>
><br>
> What I am doing first is a binary thresholding<br>
> (itk:BinaryThresholdImageFilter) and it works well. However, I don't know<br>
> how to define a cluster of bright points which make a single star. I don't<br>
> know if this make me clear. Let's try another way to clarify: how to know<br>
> which points are from the same star? any examples available in ITK?<br>
><br>
> Thanks for any input.<br>
><br>
> Tao<br>
><br>
</div></div></blockquote></div><br>