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




>From: "michael shaffer" <rarewolf@roadrunner.nf.net>
>   Because my system is calibrated, I am not assuming.  If my monitor is
>truely gamma calibrated, and I use a gamma=2.2 working color space, then a
>18% gray card's RGB value should be R=G=B=117 (see formulas below, they
>aren't mine).  I ask you ... under what circumstances would an 18% gray 
>card
>be anything else? (you may also assume I have ambient illumination under
>control.)

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.

generate an icm profile for you monitor (i.e. with a color sensor) and 
scanner and ignore the rgb values.

Regards
Ned


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