scanner and Photoshop skills?

For post processing it is important to have a high resolution. This has
nothing to do with the final result which of course has to be smaller
to fit the screen in the end.

By the way, screens do not have a fixed resolution of 72dpi. Most
screens nowadays will be running near 100dpi but this depends on the
resolution set by the user. The term dpi only really applies to
printing.

I am quite sure that National Geographic prints at a higher resolution
than 300dpi (my printer at home does 600dpi).

I still recommend not to use any kind of scanner demoiré features
because scanner software usually is not as good as Photoshop. Each
post processing step takes information from the original leaving less
options for the guy putting it all together in the end.

alex8735 wrote:
I still recommend not to use any kind of scanner demoiré features
because scanner software usually is not as good as Photoshop. Each
post processing step takes information from the original leaving less
options for the guy putting it all together in the end.

I guess the ideal scenario would be a raw-output mode for the scanner,
and a free Photoshop plugin to read the output files.

Johan Larson

alex8735 schrieb:

For post processing it is important to have a high resolution.

Agreed. However, it's all a question of economics. There's definitely no
point in scanning an entire magazine page with 1200 dpi, which will
create something like 500 MB of data, then sending this data through a
modem line, then working on this huge file, only to have it downscaled
at the end to something which will be displayed as a 15cm x 10cm picture
on a web site. Scan as needed.

I am quite sure that National Geographic prints at a higher resolution
than 300dpi (my printer at home does 600dpi).

For line art, high resolution is crucial. I can even tell the difference
between 600dpi and 1200dpi.

However for half tones (aka pictures), there's no use to set the
resolution higher than twice the printed screen frequency. Note: This is
the *theoretic* maximum of data that can be reproduced when you
rasterize a picture! Practically, with most pictures, even a factor 1.4
will yield perfect results.

Now as most magazines print with a screen of around 150lpi, the raw
material is never higher than 300dpi. (Art reproduction is a different
story because they use finer screens. And FM rasters are yet a different
story altogether.)

I still recommend not to use any kind of scanner demoiré features
because scanner software usually is not as good as Photoshop.

Replace "usually" by "sometimes", the I agree. Again, it's a question of
economics: If you want to demoiré in Photoshop, you indeed need a high
resolution scan.

Stefan