image analysis

Enrique Castro ecastro at eucmax.sim.ucm.es
Mon Feb 22 12:20:57 EST 1999

William Sun wrote:
> Hello all,
> I wish to quantitate my northern signals on autorad film.  What is the best
> and cheapest way?  Can I just scan the film with a conventional flatbed
> scanner and analyze the image with ImageQuant?  Is this accurate enough?
> Thanks for any advice.

	You can bet not. There are two separate problems in scanning films for
a) The film response is logarithmic and with reduced dynamic range (100
at most)
b) The scanning is highly non-linear too given an image where the
intensity is NOT proportional to film darkening.

Without proper calibration (difficult) this method don't give you a
better answer than your eye: this band is faint, this other is darker,
but no precise quantitation. And you eyes are 'default', 'standard',

Enrique Castro


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