I know you've got a smily face, but he was asking for a technical answer,
and if you think carefully about what each word means in the quoted
definitions, those definitions are very clear. But what he needs is a
complete answer, which I didn't give. Why do we need gamma in the first
place? I've read about it, but off the top of my hat I forget the complete
answer. The whole visual system is nonlinear: the response of the cones in
our eyes to color stimulus, the response of the phosphors to electron
stimulation, the amount of flare off our monitors, etc. I forget all the
factors. But gamma attempts to compensate for all this nonlinearity.
Frank Paris
marshalt@spiritone.com
> -----Original Message-----
> From: owner-filmscanners@halftone.co.uk
> [mailto:owner-filmscanners@halftone.co.uk]On Behalf Of Henry Richardson
> Sent: Friday, February 02, 2001 8:24 PM
> To: filmscanners@halftone.co.uk
> Subject: RE: filmscanners: This Gamma Thing...?
>
>
> >From: "Frank Paris" <marshalt@spiritone.com>
> >
> >Here is Giorgianni and Madden's definition from "Digital Color
> Management":
> >"Exponent of a power-law equation relating CRT luminance to
> control-signal
> >voltage". Also, "The slope of the straight-line portion of a CRT
> >characteristic curve relating log luminance to log voltage."
> Anyhow, that's
> >why if you play with it, it changes the appearances of images on the
> >screen.
> >You're basically changing the voltage applied to the phosphors given a
> >certain digital input value, thus changing the luminance. You're changing
> >the shape of the curve of RGB value vs. voltage applied.
>
> I bet that will satisfy his curiosity and teach him not to ask questions.
> :-) <-- By the way, notice the smiley face -- I'm only joking.
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