Beware of geeks bearing gifs !

Not all scanners are the same, cheap doesn't necessarily mean good.

Scanner technology de-mystified.

"Hey, I've seen 9600 scanners for 30 quid or so !"

Not all scanners quoted as 9600dpi can really cut the mustard when it comes to quality scanning. If you see 9600dpi then check the Optical Resolution.

Some scanners with a basic optical resolution of 300x600 are now advertised as 9600dpi.

But this is just Software Trickery ! Or rather, EVEN MORE Software trickery.

ALL scanners can use an anti-aliasing interpolation technique(*) to achieve higher dpi than the physical limit of their sensor/CCD, and 4800dpi is generally accepted as the sensible limit for a 300x600 scanner.

Some scanners have an Optical Resolution of 600x1200 making them the better choice for the higher quality scan, because it doesn't have to 'interpolate' as much; the physical resolution is four times greater. Some scanners are also 3D scanners. "What's 3D scanning ?" Well, I'm glad you asked !

Some lo-cost scanners can only scan documents, they can't focus on anything further away than the top surface of the glass. But some have a CCD lens (like a video camera) and can scan objects. So not only can you scan all your holiday snaps, you can also scan all the hideous ornaments you bought from the bazaar and have them on your desktop in addition to gracing your teak-effect sideboard.

In other words, making educated guesses about the bits it can't see by performing calculations based on the bits it can. It's the technique that Video camera's with "6 zillion times digital zoom" use, grab some pixels in the middle of the viewfinder, make them fill the screen and then try to smooth them out by guessing where the edges of the objects would be.

Sometimes it works, but it's nearly always better to use your legs and get closer. (Unless you're in a zoo filming crocodiles!)