| kernel convolution? [message #49531] |
Fri, 28 July 2006 11:16 |
adisn123
Messages: 44
Registered: July 2006
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Member |
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Hello,
I tried FFT(discrete fast fourier transform) on my spcial image and
used several different kinds of filtering application.
What I wanted FFT to do was that FFT removes both very low frequency
and high frequencies.
I thought if I do this filtering with FFT, that I could get rid of
stars in my images, but
actually it turned out to be it does not, but rather reduce the
intensity.
In my understanding, it is because FFT does fourier transform pixel by
pixel, thus if a star
lies on several pixels, say 5 x 5, FFT of this would give both medium
high freuqency around the star
edge and very high frequency at the center of the star. Thus, removing
low and high frequencies using filter would reduce the center intensity
of the star, but still it would give me the residuals of the star.
So, I'm thinking some other method such as kernel convolution (CONV
function in IDL).
I'm not sure how this works exatly. If some one know about this or
other possible method that I can choose, please reply me.
Thanks.
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