Re: fluorescence ratio

Posted by John Oreopoulos on Sep 02, 2009; 11:53pm
URL: http://imagej.273.s1.nabble.com/fluorescence-ratio-tp3691315p3691316.html

Giulia,

First, go to Analyze->Set Measurements and make sure "Mean Gray  
Value" is checked.
Next, draw a region of interest on your image with the Rectangular  
Selection tool (or circular or freehand tools if your imaging  
situation demands it. To get the mean pixel intensity value within  
your region of interest, click Analyze->Measure, and the result will  
appear as a number in a results window.

Move the region of interest to your other cell compartment where you  
want to measure the intensity value and do the same thing. Now you  
can take these two numbers and calculate a ratio by simple division.

Beyond that, if you require automation/repetition or more complex/
multiple regions of interest to be examined, you may want to try  
writing a macro that does this for you. Try looking through the long  
list of plugins available on the main ImageJ website and see if there  
is any plugin out there that already does this. None come to mind  
immediately, but perhaps there is a calcium imaging plugin that might  
do the trick for you. Hopefully someone else here on the server can  
suggest one.

John Oreopoulos


On 2-Sep-09, at 7:42 PM, Giulia Falivelli wrote:

> Hi All,
>
> I am new in Image J.
> Does anybody know how to calculate the fluorescence ration between two
> different cells compartement?
> Or how to calculate the mean grey value of a specific ROI?
> Thank you very much.
>
> Giulia