Posted by
Olivier Salvado on
Jan 16, 2006; 4:21pm
URL: http://imagej.273.s1.nabble.com/Ratio-and-Background-substraction-operations-tp3704031p3704032.html
I think that you are right in the sense that it
depends on the detector. In case of MRI for
example the bias field is multiplicative,
therefore one must divide or subtract after log
transform. In the case of microscopy, it depends
on your acquisition camera.
One way to test it, is to image a phantom with two
areas with a sharp contrast, and image a flat
background. By looking at some profiles you should
be able to figure it out.
___________________________
Olivier Salvado
Biomedical Engineering Department
Case Western Reserve University
-----Original Message-----
From: ImageJ Interest Group
[mailto:
[hidden email]] On Behalf Of Vasseur
Monique
Sent: Thursday, January 12, 2006 10:26 AM
To:
[hidden email]
Subject: Ratio and Background substraction
operations
My question is more mathematical or theoretical:
Whether the detector is logarithmic or linear in
output vs. light intensity, is it correct to do a
division to get a ratio image in both cases? Or
should it be a subtraction (?!) considering that
to remove the background from an image can be by
subtracting (if logarithmic detector) or dividing
(if linear detector)?
Monique Vasseur
Département de biochimie
Université de Montréal