Since we're all about high resolution, I thought this would be a good place to ask.

Is there ever a time where you need to scan printed material greater than 600DPI and what would be your reason to do it?

I usually scan anything but CDs at 1200 then resize to 600.

CDs at 600 then resize it to 300 because the original image is already pretty small.

Extremely detailed lineart. Hand drawn artwork. For smooth edges.

High resolution (dpi), high quality (detailed) prints with minimal, hq, or no screening whatsoever.

When you are scanning something unusually small. If you want to print it at a bigger size.

Film, Slides, or Photographs.

To possibly give you more flexibility with denoising and/or descreening the image without losing as much detail, and afterwords downsizing to 600dpi or 300dpi.

All in all, if you have good source material, scanning at high dpi will be helpful. If you have a less then stellar source, anything higher then 600dpi will be overkill.

I don't know any professional theories.
Scan them all at final image resolution, then try best processing. that all. very simple :D

600dpi is fine for printed art. But for drawn artworks and image you want to preserve even more detail, that's one of the few only reason, I'd say...

scanning resolution has little affection to the final quality. you should care about higher resolution if you got the best quality at lower resolution.
don't be fooled by just higher resolution like KgnE one.

(if there are any better scans than my 600dpis, I'll rethink it :P)

Imo..higher resolutions scanning is useful to filtering usually..as the screening is more clear and easy to take care of. 600 dpi is usually enough for most stuff.

modern scanner can go up to 4800dpi... any stuff that needs that much res ?

or does higher dpi mean it will scan better at lower dpi, too ?
so a 4800dpi scanner can scan better images @ 1200
than a 1200 scanning 1200 ? o_O

MDGeist said:
modern scanner can go up to 4800dpi... any stuff that needs that much res ?

Scanning large film negatives or slides. Other then that, nothing really needs 4800dpi.

MDGeist said:
or does higher dpi mean it will scan better at lower dpi, too ?
so a 4800dpi scanner can scan better images @ 1200
than a 1200 scanning 1200 ? o_O

I would say yes. Scanners usually use CCD sensors. Just because the sensor goes up to 4800dpi doesn't mean it can actually resolve 4800dpi. Scanning at 1200dpi on a 4800dpi sensor should result in better quality then a 1200dpi sensor scanning at 1200dpi, depending on the quality of the sensor of course.

Very low resolution's all I need because my eyes are shit and I tend to watch things small and from a distance, I think high res is for if you want to put something on a big screen for a bunch of friends or print a poster.