Genealogy Today has an article series on scanning old photographs with part one covering basic scanning information. Part two will be out soon.
Among the basics are two issues that confront most new computer users when it comes to scanning photographs and graphics: size and quality.
When you scan an old photo, you create an image file. The amount of space the file takes up on your hard disk is directly related to both the size and complexity of the photo and the resolution used when you scan it. Resolution is measured in dots per square inch (dpi). For example, doubling both the horizontal and vertical resolution going from 300 by 300 dpi to 600 by 600 dpi quadruples the size of the im age file. A 6″ x 4″ photo print scanned at 600dpi produces a 25 megabyte image! Also, the higher the resolution, the longer it takes to scan the photo. The old saying, “A picture is worth 1,000 words,” is more than true with scanned images.
Scan resolution merely determines image size. When you increase scan resolution, you increase image size. A 6×4-inch photo scanned at 110 dpi fills about half of a 1024×768 monitor screen, the typical resolution of most computer monitors today.
Images in newspapers and magazines are reproduced quite differently from photographic prints. They’re reduced to a series of small dots. When scanning these, you can easily get an interference pattern between the dots on the original and the dots scanned. Some scanners allow you to “descreen” when scanning–blurring the dot pattern so it appears more like a photograph. This process is very effective and is better than trying to overcome the screen or patterning in your photo enhancement software after you scan your image. Scanning at high resolution is another way to eliminate these patterns. To scan old engravings, set your scanner to Line Art at 600 dpi.
This are very good points to consider when scanning.
If you are scanning from old photo albums or newspaper clippings, handle these with cotton gloves to protect the emulsion and fragile quality of the items, and handle them with extreme care.
If you are removing photographs or newspaper clippings from photo albums, get professional advice if they don’t come out easily. The best advice is to scan them in their original form rather than remove them, to ensure their protection.
I’ll be writing more about scanning and using your historical images, letters, and graphics in the next few months.
Most Recent Articles by Lorelle VanFossen
- The Myths and Mysteries and Hunt for Nicholas Knapp
- The Perpetual Calendar
- GenSmarts: Reminder to Not Assume
- Gensmarts Saves Your Family History Research Life
- Digging Through Historical Newspapers Online