On Fri, 07 Mar 2008 20:03:36 -0500, tacit <tacitr@aol.com> wrote:


>
>Yes, you do need dithering for 256 colors. 256 colors is an
>extraordinarily limited amount; that's very poor color fidelity indeed.
>Remember that each shade of the same color counts as a different color.


My friend responds:

The thing about color --- particularly about fine differences between
hues of color --- is that it is completely subjective. Film --- and I
suppose CCDs as well --- is not subjective. Color depends entirely on
the color temperature of the light. Try taking a color photo with
fluorescent light to see the difference. The curious thing is that we
have color memory; if we know what color a thing should be, we will
see it that way whatever the color temperature of the light. Whites
look white to us because we know they are white. But white is made to
appear more white by tinting it most generally with blue, but also
with yellow and even black. When all the other colors were perfectly
balanced, Keeping bride's dresses from appearing blue in photos was a
challenge for me because of the optical whitening added to the fabric.

So, for purposes where actual color is not known or where critical
rendition of actual color is relatively unimportant, 256 colors will
suffice. For 4x6 snapshots, 256 is good enough. The toughest challenge
for film and CCDs is good skin tones. For a large print of a head
shot, 256 colors are inadequate. Dithering is a poor substitute for
the infinite modeling provided by film. But I shall need to learn to
apply the finest dithering the Alps is capable of to be happy with its
600 dpi resolution. I thought that my MD-4000 was capable of 1200 dpi,
but that may be for scanning only.

-Gecko