Posted by
Michael Schmid on
Nov 28, 2013; 8:57am
URL: http://imagej.273.s1.nabble.com/Low-and-high-pass-filter-tp5005690p5005724.html
Hi Vincent,
your question is not very clear...
Anyhow, for more details on the Fourier-domain filter, see this recent post (beware of a possible line break introduced by the mailer in the link):
https://list.nih.gov/cgi-bin/wa.exe?A2=ind1311&L=IMAGEJ&D=0&1=IMAGEJ&9=A&P=187719Essentially, you can do the same type of filtering with Process>Filters>Gaussian Blur (low pass) or subtracting the Gaussian blurred image (highpass). A high pass filter working like this is also available as a filter with preview:
http://imagejdocu.tudor.lu/doku.php?id=plugin:filter:highpass_filter:startMichael
________________________________________________________________
On Nov 25, 2013, at 14:02, Vincent Wolowski wrote:
> Dear all,
>
> I am trying to understand how to use the Process/FFT/Bandpass Filter
> for low- and high-pass filter on 16-bit images. I have read the
> documentation here:
http://rsb.info.nih.gov/ij/plugins/fft-filter.html> but I am not completely sure yet.
>
> I think a low-pass filter can be achieved in the following way:
> Let's say the image is 800x800 and only small objects with a size of a
> few pixels, e.g. 3 pixels, are contained.
> For a low-pass filter set the filter for large structures to 800 so
> that low frequency signals pass and the filter for small structures to
> 3 in order to filter out high frequency signals.
> Is this correct?
>
> Would a high-pass filter then be achieved in the following way?
> Set the filter for large structures to e.g. 3 and the filter for small
> structures to 800.
>
> Cheers,
> Vincent
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