In a message dated 12/14/99 3:17:56 AM Pacific Standard Time,
jribeiro@greco.com.br writes:
> I always imagined that if you have 300 lines you also have 300 dots / inch
in
> that direction.
In traditional halftoning, each dot can be variable in size. The dots
correspond directly with the line ruling of the halftone screen, so it is
called lpi. For example, if you have 60 lpi, you will have 60 dots per inch,
but each dot can be a small dot or a large dot.
For imagesetter output, each dot is fixed size. So if you output at, say, 60
dpi, each dot can be only opaque or clear, so there won't be gray scale. If
you output at finer resolution, e.g. 600 dpi, you use 10 dots in each
direction to make one "superdot," thus you have 10*10 subdots to turn on and
off, so you can make 100 shades of grays.
Now you can see that if you need 150, 300 lpi or higher, the imagesetter must
have quite high dpi.
With schocastic screening, you don't select the lip, you use the dpi but the
software algorithm alter the spacing of each dots instead of the size of
(super) dots.
Dave Soemarko
==================================================
=== See Soemarko's Direct Carbon (alternative) process at
=== http://hometown.aol.com/fotodave/SDC/SdcIndex.html
==================================================
This archive was generated by hypermail 2b29 : Tue Jan 11 2000 - 12:10:48