Re: FFT along line in image

Posted by Jay Unruh on Oct 23, 2007; 8:13pm
URL: http://imagej.273.s1.nabble.com/FFT-along-line-in-image-tp3698130p3698144.html

This is only valid if the profile plot was created earlier in the same
plugin.  Once the creating plugin has terminated the data is only
accessible via the list or copy buttons, right?  The same is true for
the axes scales, etc.

Thanks for the info about measurement options.

Jay

Wayne Rasband wrote:

> 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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>>>
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>>