At 05:44 PM 7/19/01 -0400, you wrote:
>Lynn, Rafe, Rob and others:
>
>One thing I've always been curious about is what causes the topographical
>map type of lines you see in the blue sky portion of this image:
>
>
>
>???
>
>I see this sort of artifact a lot in jpegs on the web. Is this what is
>called "jaggies?" Do they show up in prints?
Hold everything! Do you mean, "Prairie, Northern Tibet?"
If you're seeing "topo map" effects in the sky, it's
almost certainly because you have your video set to
"256 colors." There's no way you want to attempt ANY
image editing or capture with your screen set that way.
This is something you'd change (on a PC) using
Control Panel->Display->Settings.
What you want is True Color, most likely 24 bits.
Using 24 bits with a high resolution requires a
video card with a decent amount of video RAM. So
you may find that some of the higher resolution
settings are grayed out when you select 24 bit color.
The sky in the "Prarie" photo looks smooth as silk
on my PC, with 24 bit video. With the screen set
to "256 colors" I get topo maps in the sky.
Get yourself an up to date video card, with at least
8 or 16 Mbytes of video RAM. Matrox is a decent pick
for graphic arts and 2-D images.
Jaggies are an altogether different matter; they're
a consequence of scanning and/or printing at too low
a resolution. For example, if you were to try to
grab this little image off the web, and print it as
8x10" on your Epson, you'd get "jaggies."
There are ways to smooth out jaggies, but they
invariably involve softening the image.
rafe b.
