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MathGroup Archive 2006

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Re: Re: Counting circles (digital image processing)

  • To: mathgroup at smc.vnet.net
  • Subject: [mg64548] Re: Re: Counting circles (digital image processing)
  • From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>
  • Date: Wed, 22 Feb 2006 05:58:30 -0500 (EST)
  • Organization: Uni Leipzig
  • References: <dte258$rde$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi, and huuu

K-means and all of its variants work on the 
distribution of the
pixel values and do abolut nothing with the 
geometrie
of the objects shown in the picture ...

The OP need the number of extended geometric 
objects, in
the worst case that are white circles on an black 
background
and the distribution has a peak at 0 and one at 1 
and nothing
more ... K-means will find the threshold to 
binarize the image
if it is nor already, but it will never find 
connected pixels.

The image processing package has a connected 
component labeling
*and* a distance transform (don't know which one) 
and it should be
simple to count the circles and get the radius. 
The only
problem may be, that the images are extrem noisy 
or the circle shape
can be seen only when one looks at the gradients 
of the image and not
onto the intensity, but in both cases K-means help 
nothing.

Regards
  Jens

"Maarten van der Burgt" 
<maarten.vanderburgt at icos.be> schrieb im 
Newsbeitrag news:dte258$rde$1 at smc.vnet.net...
|
| Hallo,
|
| I think the function KMeans[ ] in the Digital 
Image Processing package is
| the clustering function you are looking for.
| Have a look in the User`s Guide section 7.5 
Segmentation by Clustering.
|
| Maarten
|
|
|
||--------+--------------------------------->
||        |          "Jens-Peer Kuska"      |
||        |          <kuska at informatik.uni-l|
||        |          eipzig.de>             |
||        |                                 |
||        |          18/02/2006 08:49       |
||        |                                 |
||--------+--------------------------------->
| 
 >------------------------------------------------------------------------------------------------------------|
|  | 
|
|  |       To:     mathgroup at smc.vnet.net 
|
|  |       cc: 
|
|  |       Subject: [mg64548]      Re: Counting circles 
(digital image processing) 
|
| 
 >------------------------------------------------------------------------------------------------------------|
|
|
|
|
| Hi,
|
| label the connected components in the binarized 
image.
| For the radius I would suggest to use a distance 
transform on
| the binary image and the maximum value of the 
distance transform
| in every single unconnected component is your 
radius
|
| Regards
|  Jens
| "Alexander" <beginning.physst at mail.ru> schrieb 
im
| Newsbeitrag news:dt488e$2hk$1 at smc.vnet.net...
|| Dear Mathgroup!
||
|| Suppose we have a picture with a set of white
| circles on a black
|| background.
|| How can we count circles and measure their
| radius using mathematica
|| system???
||
|| Thanks for your answers!
|| Alexander.
||
|
|
|
|
|
| 



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