Inquiring Minds on Photo Scans

I received a phone call from a friend with a question about photo preservation. She has several thumbnail-sized pictures of ancestors. In some cases, it is the only picture that they have of the individual and she wants to make sure that they preserve these images in the best way possible. All of us can relate. Who doesn't have teeny-tiny pictures in our collection of family faces? Some of our photographs have been cut into oval shapes and dutifully pasted into genealogy records by those doing the best they could with the technology of their day.

So, given the wonderful technology of the 21st century, what is the best method for digitally preserving these pictures? We usually recommend scanning pictures at 300 dpi. This will create a file that is more than adequate for regular viewing and in most cases will let you enlarge the picture without sacrificing resolution. We know that the .tiff format offers a higher quality image as it is uncompressed, but it comes at the price of big (sometimes enormous) file size! Here is Brenda's question in a nutshell: Is it better to scan these little pictures at a high resolution, say 600 or even 1200 dpi, and save them in .jpg format, or will scanning them at a lower resolution in .tif format improve their resolution?

We did a quick experiment on Great-grandma Ellen. Thanks for helping, Grandma! This picture only measures .75 inches x 1.0 inch. To add to the dilemma, the image happens to be a copy of a long-lost original. We scanned the picture at 300 and 600 dpi (dots per inch) in both jpg and tiff formats. The file sizes ranged from 59 KB to just over 1MB.

300 dpi jpg = 59 KB
300 dpi tiff = 252 KB
600 dpi jpg = 241 KB
600 dpi tiff = 1.07 MB

There is virtually no visual difference in the resolution of any of our pictures. The print size of the 600 dpi is more than double that of the 300 dpi scans, but the smaller files enlarged easily and there is no noticeable difference in resolution when they are printed. Does this mean that we'll be happy with the outcome of pictures scanned at 300 dpi?

Please share any information you have on the best method for preserving small photographs. Inquiring minds want to know!