| Re: Image filtering [message #16059] |
Wed, 30 June 1999 00:00 |
gabriel rodriguez ibe
Messages: 10
Registered: July 1999
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Junior Member |
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Robert B. Bohn escribi�:
> Dear Folks,
>
> I'm trying to do some blob filtering on an 8 bit B&W image (TIFF
> file). The range of the bits is 0-255.
>
> I am trying to clean up the image and remove extraneous black
> spots from white fields and vice-versa. In terms of BLOB filtering,
> I am trying to perform a "close" operation.
>
> Any suggestions how to do this with IDL?
>
> Sincerely,
>
> Bob Bohn
> email: robert.bohn@nist.gov
>
> --
> Dr. Robert B. Bohn
> High Performance Systems & Services
> NIST
> 100 Bureau Dr, STOP 8951
> Gaithersburg, MD 20899-8951
> phone: 301-975-4731
A non linear filter that may apply is the MEDIAN filter. IDL has a
function with the same name. That filter will eliminate the black/ white
spots from a white/black surrounding WITHOUT CHANGING any other values
(the ones that are supposed to be correct), provided that the errors are
relatively not frecuent.
Other linear filters will change the values of all pixels, and probably
not eliminate the spots very clearly, unless you choose a big window, in
wich case borders will get fuzzy.
In any book on image processing you will see easy to understand
examples.
Hope it helps.
Gabriel
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| Re: Image filtering [message #16096 is a reply to message #16059] |
Mon, 28 June 1999 00:00  |
David Foster
Messages: 341
Registered: January 1996
|
Senior Member |
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Robert B. Bohn wrote:
>
> Dear Folks,
>
> I'm trying to do some blob filtering on an 8 bit B&W image (TIFF
> file). The range of the bits is 0-255.
>
> I am trying to clean up the image and remove extraneous black
> spots from white fields and vice-versa. In terms of BLOB filtering,
> I am trying to perform a "close" operation.
>
> Any suggestions how to do this with IDL?
>
> Sincerely,
>
> Bob Bohn
Bob -
Look at the ERODE() and DILATE() functions. You might also have a
look at CONVOL() for more general purpose convolutions.
Dave
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~
David S. Foster Univ. of California, San Diego
Programmer/Analyst Brain Image Analysis Laboratory
foster@bial1.ucsd.edu Department of Psychiatry
(619) 622-5892 8950 Via La Jolla Drive, Suite 2240
La Jolla, CA 92037
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~
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