Digital ICE is a technology which works specifically with transparent and semi-transparent materials like photographic film. It fairly reliably reduces or eliminates dust, scratches, and dirt that would be otherwise visible in a scanned image, without loss of quality of the underlying image. It uses a combination of hardware and software, so it’s generally integrated into a slide or transparency scanner, much like the one we use here in the lab. It’s not something you can simply download for your existing scanner. Also, because of the way it works, it does not have an effect on scans of opaque objects like photographic prints.
Here’s a real-life example:
This is a crop from a scan of a slide taken in the 1960s. On the left, you can see all of the dirt, mold, dust, etc. that has accumulated on the surface of the film. This would be nearly impossible–or ridiculously time-consuming at the very least–to clean up in Photoshop. But the right-hand image shows you that turning on Digital ICE cleans up the dirt almost magically.
There are a couple of small drawbacks to Digital ICE. The first is that it slows down the scanning process. The second is that you will notice a slight decrease in sharpness, but nothing that can’t be easily rectified in Photoshop with unsharp mask.
You can turn Digital ICE on in Nikon Scan before you start scanning slides. Ask the lab consultant on duty if you need help.