Posted by
Daniel White on
Dec 08, 2014; 8:36pm
URL: http://imagej.273.s1.nabble.com/Fwd-possible-bug-in-the-ImageJ-Coloc-2-tp5010830p5010851.html
Hi guys,
Perhaps we should be using a simple linear regression (if that's what
Costes says to use) from a stats package instead of rolling our own?
Apache commons math? Or does that just add overhead....
Honestly the maths is beyond me here. I get what a least squares method
should do. But the calculations doing it all in one go stretch my maths
past its limit. So I will leave it to those who have better grasp of it.
As usual, watch out for numerical weirdness eg if image means are the same.
Write a unit test if you can and should, which takes generated data as
input with a well known regression result or set of results. Eg we can
generate pairs if values for a known linear function. Add a but of Gaussian
white noise. And we should get a good fit and the same linear equations
back out.
Hope that helps.
cheers, Dan
http://chalkie.org.ukOn 8 Dec 2014 17:57, "Tom Kazimiers" <
[hidden email]> wrote:
> Hi,
>
> @Dan: Thanks for putting me on CC!
>
> On Mon, Dec 08, 2014 at 03:01:08PM +0100, Daniel White wrote:
> > I'm not sure if it's bug or not. It's certainly possible. But I haven't
> got
> > time to look into it. Perhaps Tom has. Perhaps not.
>
> Sorry, I probably won't have time to look into this until the end of
> this week, likely not before Friday.
>
> I also remember vaguely that we had a discussion around August last
> year, where we spotted a problem with the linear regression as well. The
> problem there was that different thresholds are found if the order of
> input images is reversed. Now that this comes back to my mind, I don't
> think we actually fixed this. I'll have a look at both problems, maybe
> they are related.
>
> Best,
> Tom
>
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