[Numpy-discussion] numarray.nd_image.label() help

Russell E Owen rowen at u.washington.edu
Wed Jun 2 12:43:03 CDT 2004


At 2:49 PM +0200 2004-06-02, Andrew Wilson wrote:
>Hello,
>    I'm having some trouble with the numarray.nd_image.label() 
>function as it is not connecting two objects (that are adjacent) on 
>some images.  I have tried using the struct:
>                   [[1,1,1]
>struct  =      [1,1,1]
>                     [1,1,1]]
>
>this does change how it is connecting various objects in my image 
>(as compared to the default struct) but it still splits the objects 
>eventhough they are touching.  Any hints or clues?  I could send the 
>pictures, just don't want to post them to the entire list.

I use it and have not (yet) noticed this, so I hope it's something 
you're doing and not a bug.

You could try generating a boolean version of your image, examine 
that to make sure the objects are still adjacent on that and use 
label on it. Here's my code:

   import numarray as num
   # smoothed data is a median-filtered version of my image
   # dataCut is a value above which pixels are considered data
   shapeArry = num.ones((3,3))
   labels, numElts = num.nd_image.label(smoothedData>dataCut, shapeArry)

If this doesn't do it (and nobody has anything better to offer), 
please put the image up somewhere that we can access it and show us 
your code.

-- Russell




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