RE: filmscanners: creating correction curves from scanned calibration chart?

["Ned Nurk" <ned_nurk@hotmail.com>]

jeez its late and i've had too many beers but ill give it a go.

(extreme example) imagine we had a linear luminocity scale of 0-100 (0% to 
100%) and these are represeted in values in a file between 0-100. The best 
device you have got can represent say 10%-90%. anything below 3 or above 96 
is clamped at the respective values. that means your entire contrast range 
can only be expressed in the 80 steps between 10 and 89, thus leaving 20 
values unavailable to be used.

If we all agreed that the 0-100 values in the file mapped to the real values 
of 10% to 90%, then we have 100 steps of contrast different between the two 
points?

Not making sense? hmm, even I'm not sure what I'm writing at the mo. This is 
my last mail on the subject.  topic closed.

further reading: 
http://www.inforamp.net/~poynton/notes/colour_and_gamma/ColorFAQ.html

warmest regards
Ned (or Ed as shAf called me, lol)

>From: "Austin Franklin" <darkroom@ix.netcom.com>
>Reply-To: filmscanners@halftone.co.uk
>To: <filmscanners@halftone.co.uk>
>Subject: RE: filmscanners: creating correction curves from scanned 
>calibration chart?
>Date: Sun, 11 Nov 2001 14:54:01 -0500
>
> > your assumption being that 0,0,0 is totally black and 255,255,255
> > is totally
> > white in that 2.2 gamma colour space. Would be a pretty daft
> > colour space as
> > you can't get either on a monitor or printer and so you end up wasting a
> > whole bunch of values that could never be properly expressed.
>
>Huh?  Would you elaborate on this please.
>


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