Re: Raw versus calibrated integrated density

Posted by IJperson on Oct 18, 2010; 2:42pm
URL: http://imagej.273.s1.nabble.com/Raw-versus-calibrated-integrated-density-tp3686613p3686615.html

Hi Michael.

Many thanks for the reply.
To clarify, I am not referring to greyscale calibration. Lets assume I am just interested in the intensity of the pixels as they appear, with no extra scaling.  My confusion lies with different integrated intensities (IntDen and RawIntDen) over spatial calibration.

The example you present with Watts is helpful.  So the integrated density has units:
 cm * cm * W/cm^2 = watts.  I.e. The spatial units disappear.

So the calibrated (IntDen) has units:
<realworld unit> * <realworld unit> * <intensity unit>  / <realworld unit>^2  =<intensity unit>

and the uncalibrated (RawIntDen):
<pixel unit> * <pixel unit> * <intensity unit>  / <pixel unit>^2                    =<intensity unit>

I.e. both have the same unit, which appears to be independent of a spatial dimension. So should both therefore have the same value?

I expect I am still misunderstanding something, but this is a very helpful discussion.

Many thanks
Andrew