Re: FFT along line in image

Posted by Wayne Rasband on Oct 23, 2007; 6:53pm
URL: http://imagej.273.s1.nabble.com/FFT-along-line-in-image-tp3698130p3698143.html

A plugin can get the line profile data using

     ProfilePlot pp = new ProfilePlot(imp);
     double[] array = pp.getProfile();

where 'imp' is an ImagePlus with a line selection. Macros can use

     profile = getProfile();

The number of decimal places used by the "List" button (up to 9) can be  
set in the Analyze>Measurement Options dialog box.

-wayne

On Oct 23, 2007, at 12:34 PM, Jay Unruh wrote:

> 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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>