RE: filmscanners: This Gamma Thing...?

["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.

Frank Paris
marshalt@spiritone.com
http://albums.photopoint.com/j/AlbumList?u=62684

> -----Original Message-----
> From: owner-filmscanners@halftone.co.uk
> [mailto:owner-filmscanners@halftone.co.uk]On Behalf Of Tom Christiansen
> Sent: Friday, February 02, 2001 7:07 PM
> To: filmscanners@halftone.co.uk
> Subject: filmscanners: This Gamma Thing...?
>
>
> Hi,
>
> I've learned a new word today: Gamma.
>
> It's something with the way monitors show images, but what
> exactly is it??
> I notice that my scanner software has a gamma adjustment and playing with
> it I noticed that it changes the way the image appear on the screen.
>
> But what exactly is this mysterious gamma thing?
>
> My scanner software defaults to gamma=1.4. It this an optimal value? If
> not, what is a better value?
>
>
> I'd appreciate some scientific facts about this gamma.
>
>
> Thanks,
>
>       Tom
>