Posted by
LMAnovitz on
May 13, 2009; 8:47pm
URL: http://imagej.273.s1.nabble.com/1D-autocorrelation-function-tp3692494p3692499.html
Hi,
A few weeks back, Gabriel was kind enough to send me the suggestion
below in response to my question about a plug-in to calculate 2-point
correlation functions.
Having been working with this plug-in for a few weeks now, I have run
into a couple of problems, and one query, which I hope someone can help me
solve.
The biggest problem is memory. Running this plug-in takes a lot. If I
have a 1024 x 1024 pixel image I can get it to solve if I set the memory to
2 GB, If I have a 2048 x 2048 image I have not yet gotten the program to
work. Instead, it comes back with a window saying that it has used up the
available memory (I've used values as high as 4 GB, and downloaded the
newest version of ImageJ for the Mac this afternoon). While I have tried
down-sampling the image, and this works, it does not give me the resolution
I would like, and I need to keep the overall image size large to avoid edge
effects (I'd like to go to a 4096 x 4096 image at least).
The second problem is that the "naïve" computation version of the plug
in does not seem to work at all. The pop-up window does say that this is
slow, but I've left if for hours without any results.
Finally, a question. The plug-in has a default radius step (changeable)
of 0.3 pixels. Since this is (obviously) less than 1 pixel, and the
correlation has to do with the relationship between pixels, this seems a bit
odd. I suspect it may be due to the FFT method of obtaining the
calculation, but am not sure, and was wondering if Dsho (who wrote the
plug-in) could enlighten me.
Many thanks in advance for help with this.
--Larry
I am running a Mac, with system version 10.5.6, a 2 x 3.2 GHz Quad-Core
Intel Xeon processor, and 6 GB of 800 MHz DDR2 FB-DIMM memory.
--Larry Anovitz
--
Dr. Lawrence M. Anovitz
MS 6110 PO Box 2008
Aqueous and Geochemistry Group
Oak Ridge National Laboratory
Oak Ridge, Tennessee 37831-6110
865-574-5034 : phone
865-574-4961 : fax
[hidden email]
On 4/6/09 10:46 AM, "Gabriel Landini" <
[hidden email]> wrote:
> Larry,
> Are you sure you do not mean the "two-point correlation function"? That is a
> commonly used technique in condensed matter physics (I have seen it several
> times used to characterise fractal agglormerates and porous materials).
>
> Dsho wrote a plugin some time ago. I have not used it, though:
>
>
http://wbgn013.biozentrum.uni-wuerzburg.de/ImageJ/two-point-correlation.html>
> Cheers,
>
> G.