Re: FFT along line in image

Posted by Gluender on Oct 23, 2007; 6:52pm
URL: http://imagej.273.s1.nabble.com/FFT-along-line-in-image-tp3698130p3698141.html

Dear Jay Unruh,

can't follow you with the precision issue. You
can conveniently access all IJ data with the
appropriate decimal precision by using IJ-macros.
Furthermore, import and export of data to and
from IJ is straightforward.

Best

Herbie

>I will echo this sentiment.  It would be straightforward to do these
>analyses if the line data were available to a plugin.  Unfortunately, one
>has to obtain this data through the List button which reduces the data to
>three decimal points precision.
>
>Jay
>--
>Dr. Jay Unruh
>Laboratory for Fluorescence Dynamics, Room 3311
>Natural Sciences 2 Building
>University of California, Irvine
>Irvine, CA 92697
>Phone: [phone]
>
>>  On the contrary, this has everything to do with "image processing":
>>  there is no reason why "images" have to be 2-D and probably the
>>  greatest weakness of ImageJ (don't get me wrong - I think it's
>>  great!) is the inability to assign different scales and meaning to
>>  different axes of arbritrary dimension.   Yes, there are plugins, but
>>  this needs to be at the heart of the ImageJ data model.
>>
>>  A sonogram (x=frequency, y=time) is usually displayed as an image.
>>
>>  Rick
>>
>>  On 23 Oct 2007, at 5:10 pm, Gluender wrote:
>>
>>>  Dear Jon Harman,
>>>
>>>  what you are looking for is the 1D Fourier Transformation which has
>>>  no direct relation to image processing. Consequently, you may have
>>>  a look at general signal rpocessing software. You will find a lot
>>>  of free 1D FFT code in the internet. I sometimes use a macro that
>>>  comes with Kaleidagraph that in turn can be use in a demo mode for
>>>  free (Mac & Windows versions available).
>>>
>>>>  Hi,
>>>>
>>>>  Is there a plugin to ImageJ that can calculate the FFT along a
>>>>  line in the image and display the result (say for instance plot
>>>>  the power spectrum)?
>>>>
>>>>  Jon
>>>
>>>  I suggest to export the line data etc.
>>>
>>>  If precision and computational effort is not an issue you may even
>>>  apply a 2D FFT to the line (set the rest of the image to zero) and
>>>  you will get the Fourier spectrum of this line projected in one
>  >> dimension.
>  >
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