Dear Dr Jalink,

     I strongly recommend that you ask for Bio-Rad Technical Note
     Numbers 10 and 11 which explain the colocalization calculations as
     well as practical considerations such as removing bleed-though
     prior to colocalization analysis. You can ask for these from our
     microscopy Web site : http:\\microscopy.bio-rad.com

     Best regards

     Anna Smallcombe PhD
     Senior Applications Specialist
     Bio-Rad Microscopy Division


______________________________ Reply Separator _________________________________
Subject: Re: colocalization, more specific
Author:  Confocal Microscopy List <[log in to unmask]> at
Internet
Date:    28-2-2001 5:48 pm


Thanks for those suggestions.

But before trying to track down all those pieces of software to run our
data through, what is the basis of quantification? More specifically,
what statistical (or other) math is used to come to a number that
describes just how well 2 images colocalize? I have tried a bit using
e.g. correlation coeeficient of paired pixel intensities, or covariance,
or Pearsons regression coeeficient, and roughly get numbers that give
what you expect. But how significant are those values (without putting a
full month into trying to calculate that)? For example, I noted that if
I make 2 images of the same channel, one noisy and the other nice and
smooth by averaging, I get correlation coefficients that are worse than
in the case that I take 2 times that smooth image, one of which is
rotated by 90 degrees (which clearly is a wrong result).

Regards, Kees

--

Kees Jalink Ph.D.
The Netherlands Cancer Institute, dept. of Cell Biology H1
Plesmanlaan 121, 1066CX Amsterdam, the Netherlands
020-5121933 (tel office)/ ...1947 (tel lab) / ...1944 (fax) /
[log in to unmask] (email)
at home: Paulus Potterlaan 5, 2102CC Heemstede
0235-476047 / [log in to unmask]






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