What DPI to Scan Old Photos
Scan standard photo prints at 600 dpi. Use 1200 dpi for small prints, wallet photos, or anything you plan to enlarge. Scan negatives and slides at 3000 to 4000 dpi. Always scan in color, even for black and white photos, and save an uncompressed master file.
The short answer
Prints: 600 dpi. Small prints and anything you will enlarge: 1200 dpi. Negatives and slides: 3000 to 4000 dpi. Scan in color regardless of the photo, and keep an uncompressed master file.
Why 600 for prints
At 600 dpi a standard print has enough resolution to be reprinted at the same size, cropped a little, or restored, without you ever seeing pixels. Going higher on an ordinary print usually just records the texture of the paper and multiplies the file size. The exception is a physically small original: a wallet photo or a Polaroid has less image to begin with, so 1200 dpi earns its keep.
Why film needs much more
A 35mm negative is about 24 by 36 millimetres. To turn that into a file you can print or restore, you need thousands of dots per inch, not hundreds. This is also why a flatbed without a proper transparency unit does a poor job on film.
Always scan in color
A black and white print carries subtle tone and grain across all three color channels of the scanner. Scanning it as greyscale throws that away. Capture color, and convert later if you want.
Keep a real master
Save the untouched scan as TIFF or PNG. Do your restoration and sharing from copies. A JPEG master quietly loses quality every time it is edited and resaved.
Doing it on iPhone with Aion
If you are scanning with a phone rather than a flatbed, Aion captures the print with the camera, and its Improve Quality treatment rebuilds resolution for print. See how to restore old photos on iPhone.
