🚀 go-pugleaf

In article <1992Aug11.175237.2406@usace.mil> pace@tabarzin.usace.mil (Joe Pace) writes:
>Hello,
>
>   Would anyone have reccommendations for a good quality color
>scanner (256 color, about 600 DPI) and color printer (up to
>8.5x11 output, 256 color, about 600DPI)?  I know this is
>a pretty generic request, but generic responses are appreciated.
>The application involves scanning color photographs of damaged
>structures for on-line access by engineers.  A color output
>device would be needed to make hardcopy and should be able to
>render the original in near photographic quality.  
>
>As an aside... is 600 DPI good enough?  We have been looking at
>a Tangent drum scanner that has very tight registration at 1000 DPI,
>but at $170,000, it's a little pricy.  Another machine we've
>been considering is the Cannon CDC-500, a 400 DPI color scanner,
>printer, and color copier.  It sells for about $70,000.


Here's the quick lesson of print quality, as I've learned from DTP
experience:

Input resolution, as far as VISUAL OUTPUT QUALITY is concerned, does not
depend on the resolution of the scan. Higher resolutions give you more
definition, to be sure, but only if you have the output capability able
to accurately reproduce that input.

The funny thing is, input and output are NOT 1:1; that is, you need not
scan at 600 dpi to get the best possible output from your 600 dpi
printer. The actual resolution relates to the best possible screen
frequency (lpi, which is not the same as dpi) possible at your printer's
resolution. For 600 dpi, this is around 100 lines per inch (lpi)
optimally; a nominal setting is 75-80 lpi.

Here's the confusing part: All you really need for accurate reproduction
of a greyscale or color image is twice as much resolution as you expect
to have available in screen frequency at output; i.e. if you have a 600
dpi printer for output, you only need to scan at between 160 and 200
dpi.

This all sounds hokey, I know, but this is from experience. I have been
playing with desktop scanners and typesetters (1200-3400 dpi output
devices) for years now, and this is the concensual decision of many
people.

Hope that helps!

--Purp, publishing fool.
-- 
+---------------+------------------------------+-----------------------+
| Jim Meyer     | If I express an opinion, you | purp@wixer.cactus.org |
| Austin, Tejas | can bet no one else agrees.  | aka jimpurp@pro-lep   |
+---------------+------------------------------+-----------------------+