For 150 years, film reigned supreme. But today our photo archives are in danger of being lost forever as prints fade and the emulsion on slides and negatives dry out and deteriorate. If you want to be able to pass your photos (and your parent's photos and their parent's photos) on to future generations, you'll have to do it digitally.
Plan before you scan
Obviously, the first step toward restoring your old photos digitally is to scan them into digital files. But if you want to get a good digital copy of an old photo, it pays to plan ahead. There are a few things you can do to improve the quality of your scanned photos before you ever turn on the scanner.
Consider your source material, for instance. You can scan whatever you happen to have: prints, negatives, or slides. But if you have both prints and negatives stored in the attic, I'd pass on the prints and use the negatives instead (assuming they are in as good or better shape). The same goes for slides: They're preferable to prints, unless they're damaged. Negatives and slides are best because the inks used to print photos tend to fade quickly and unevenly, adding an undesirable colour cast to the photos. That's why old photos often have a reddish or yellowish hue.
If you're working with prints, it's worth pointing out that you shouldn't try to clean or improve them. It's easy to ruin old photos by over-handling. If your prints are dusty, use a dry cloth to gently wipe away the grime -- and that's all. If something is stuck on, leave it there. Most importantly, never use any kind of liquid to try to clean a photo. If your photo is torn, don't try to fix it with tape -- especially on the print side. Most adhesive tapes discolour over time, and you'll likely end up with a yellowish stripe running across your photo.
We're almost ready to scan. Before you start, clean the platen -- that's the glass scanning bed of your scanner. To do that, apply a small amount of cleaning liquid to a cloth and wipe the glass. Don't apply liquid directly to the platen, because it could leak into the mechanism. Make sure the glass is completely dry before you lay a photo on it.
Scan your old photos
Now we're ready to scan. But what settings should you use? It really depends on the way you intend to use your digital files. If you were planning to upload a digital copy to your Web site, for example, you might use the scanner's lowest resolution. However, I'm going to assume that generally when you're scanning old photos, your goal will be to restore and archive them for future generations. So let's scan them so that high-quality prints can be made from the files.
Most scanner software lets you specify the target print size and resolution in dots per inch. A good rule of thumb is to set up your scanner software so it'll create 300-dpi prints at whatever maximum print size you expect to make -- usually about 8 by 10 inches.
If your scanner software makes you specify the scanning resolution of the initial image rather than the final print size, then you'll need to do some math. To get the scanning resolution, divide the target print size by the size of the original, then multiply that by 300. You'll need a very high resolution to create usable prints from slides and negatives, since their surface area is so small. For example, if you're scanning a 1.5-inch-wide 35mm slide, you'd need to set the scanner resolution to about 3000 dpi.
After the scan is complete, save your photo as a TIFF or as a JPEG at the highest-quality setting with the lowest file compression. If you add any compression to reduce the file size, you'll be throwing away image quality.