My understanding as to a short answer is that essentially the gamma curve is
inverse to the curve of the phosphors' luminosity - one is concave, the
other convex. I'm really not clear either, though. I've read a lot but it
hasn't really hit home.
Maris
----- Original Message -----
From: "Frank Paris" <marshalt@spiritone.com>
To: <filmscanners@halftone.co.uk>
Sent: Saturday, February 03, 2001 12:42 AM
Subject: RE: filmscanners: This Gamma Thing...?
| 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.
| > _________________________________________________________________
| > Get your FREE download of MSN Explorer at
| >
|
|
