Tom writes ...
> ...
> 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.
More than monitors, most devices have a specific gamma associated
with them ... scanners, printers, digital cameras.
> But what exactly is this mysterious gamma thing?
Each device has an associated "black" and "white", both of which
are generally similar across all devices (forget for now the color of
white, eg warm vs cold). Between black and white however, is how a
device responds to the data (eg, monitor), or its stimulation by light
(eg, camera+film). This response is generally refered to as the
device's "gamma".
This type of response is complex, but can be simplified and
modeled by a mathematical power function ... the gammas we all refer
to as (eg) 1.8, or 2.2, even 1.4 are exponents of this power function
called gamma.
> My scanner software defaults to gamma=1.4. It this an optimal value?
If
> not, what is a better value?
It may indeed be your scanner's optimal value ... like I said,
each device has its own. However, don't let the math intimidate you.
The important parameters to first understand are "black" and "white"
... if everything inbetween looks good, then your gamma is probably ok
too. To get it perfect ...
further reading:
Charles Poynton's color and gamma FAQ:
If you use Photoshop:
"Basic Color Theory for the Desktop"
nighttime reading:
Bruce Fraser's "Real World Photoshop"
shAf :o)
