Re: Curious about correcting exposure times for time-series imagesets

Posted by Kinata on Feb 16, 2010; 8:04pm
URL: http://imagej.273.s1.nabble.com/Curious-about-correcting-exposure-times-for-time-series-imagesets-tp3689371p3689374.html

Thanks Michael and Herbie for your help. Much to learn about
in this very interesting field.

I'm helping my son with a 6th grade science project, so extreme accuracy
isn't important. He's investigating the effect of electric fields on
nutrient
transport in plants as represented by the rate of absorption of fluorescent
dye in sample leaves. We're only interested in the relative differences
between
having a positive field gradient, reversing it, and having no field.

I was helping him with automating a _very_ basic image analysis procedure,
so that we could arrive at a curve of the area of the leaf containing dye
(without
regard to the quantity of dye at a particular pixel) versus time. We had the
Canon
software which gave us incomplete control over imaging parameters. (There's
a cool package called the Canon Hack Development Kit, described at
chdk.wikia.com, but alas, our Canon isn't supported.) After we saw that
the exposure times were quite variable, I played with various arbitrary
algorithms for scaling image brightness proportionally, and soon realized
that I didn't have much foundation for assuming anything about a
mathematical
function that associates exposure time and image brightness. This left only
an empirical approach using a reference card containing grayscale levels.

In case you're curious, you can view a time-lapse video of a series at
www.youtube.com/watch?v=lCA-icUim6M

Best regards,
Chris