Using Photoshop for densitometry?

David Tak Yan Yu dtyyu at
Wed Dec 20 19:18:39 EST 1995

We use NIH-Image instead of Photoshop.  The advantage of NIH-Image is that it 
has a curve fitting function to find out the best formula to fit the 
calibration parameters into the curve for reference.  If your curve turns out 
to be linear anyway, you might not need anything else.  Alternately, to 
satisfy the reviewer, you might like to analyze the data with curve fitting 
David Yu

In article <rdlab.62.001184AA at> rdlab at 
(rlab davis) writes:>From: rdlab at (rlab davis)
>Subject: Using Photoshop for densitometry?
>Date: Thu, 14 Dec 1995 17:30:58

>We recently began using Adobe Photoshop to quantitate signals on Northern 
>blots after we lost access to a densitometer.  We determined a range of total 
>RNA loaded in which the signals from our mRNAs of interest were linear, and 
>the data we obtained using the scanner + Photoshop agreed with our earlier 
>densitometry data.  A colleague who used similar quantitation methods recently 
>had problems with a reviewer who said this quantitation technique was not 

>My question is: Can Photoshop validly be used to quantitate signals on 
>autoradiographs?  If so, what conditions/guidelines must be followed?  Also, 
>any relevent references would be appreciated.

>Martin Hoyt
>Mol. Biol. and Biochem.
>Univ. Calif., Irvine

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