Photo Scanning Tips

The first thing you should always ask yourself before scanning is:

“What am I going to use this for?”

There are 2 basic responses:

1. Print – create a card, insert into a letter, etc.
2. Screen – view only with the computer monitor via email or web

These two mediums need to be scanned differently.

Screen

This is so easy – SCAN ONLY at a resolution of 72 ppi

Why? – monitors only display images at 72 ppi (pixels per inch)

If you scan the image at a higher resolution the screen will still display it at only 72 ppi, compensating by making the image look bigger on the screen. That’s why when you visit some personal web sites images can appear too large and force you to scroll.

For example,
A 4x5 photo scanned at 72 ppi will appear as 4x5 on your screen
A 4x5 photo scanned at 144 ppi will appear as 9x10 on your screen

“If I can’t change the ppi but I want to change the size of the photo what can I do?”

The options box in your scanning software will let you specify the size percentage (change to 50% or 200%, etc) and also the actual pixel size by width and height. Choose one or the other. The maximum size you will want your image to be in most cases is 480 x 640. That will completely fill the screen of older 14” – 15” monitors. 240 x 320 is probably a good rule of thumb measure because usually you won’t want to fill the whole screen.

TIP: For the best quality, scan exactly to the size you intend to use. Altering the image afterwards in an image-editing program risks degrading the quality of the image.

Print

To scan an image for print, scan at a resolution of either 150, 200, or 300 dpi (dots per inch). Experiment to see which your printer handles the best. Or, check your printer documentation for the maximum resolution. Scanning above 300 won’t really improve the overall printed quality.

“What if I want to do both – screen and print?”

The best and only real answer is scan it twice – once at 72 ppi and then at a higher resolution for print.