| Re: Question on watershed segmentation [message #42233 is a reply to message #42230] |
Fri, 14 January 2005 10:49  |
Karsten Rodenacker
Messages: 98
Registered: July 1997
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Member |
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On 14 Jan 2005 10:38:53 -0800, Pravesh <praveshsubramanian@yahoo.com>
wrote:
> has anybody used watershed from the idl lib?
>
> When we use watershed, the returned array consists of integers that
> number the regions that belong together.
> 0's indicate the boundary of these regions.
> so, if from a watershed-segmented image, i want to extract data for a
> particular segment only, how do i do it?
> the fact that a logical segment in an image can contain a number of
> segment obtained from watershed should be taken into consideration.
That is just the drawback and the advantage of the watershed
transformation. It is upon you to merge the parts which are distinct under
watershed following your logics and necessity.
> if the image can be divided into 6 logical segments, how do i get the
> data(say, no. of pixels) for segment number 3 that consists of say, 500
> small segments (watersheds!) obtained from watershed function.
>
One way to reduce the so called oversegmentation can be the preprocessing
of the data e.g. by smoothing (gaussian, nlg, opening, closing etc)
another is to try to merge the segments by certain criteria.
Surprising is that I just yesterday asked David Fanning for possible graph
implementations to design merging operations of watershed results. And
today somebody else asked for graph algorithms too. Nice how things come
together.
Regards
Karsten
--
Karsten Rodenacker
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GSF - Forschungszentrum Institute of Biomathematics and Biometry
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Karsten.Rodenacker@gsf.de | http://ibb.gsf.de/ | DEL _ for reply
http://ibb.gsf.de/homepage/karsten.rodenacker/
Tel: +49 89 31873401 | FAX: ..3369
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