Digital Photography: The Missing Manual

Changing the Size of Your Photos

Resizing your photo brings you up against a pretty tough concept in digital imaging: resolution, which measures, in pixels, the amount of detail your image can show. Especially confusing is the fact that the resolutions you want for printing and for onscreen use (like email and the Web) are quite different. That’s because it takes many more pixels to create a good-looking print than you need for a photo that’s going to be viewed only onscreen. A photo that’s going to print well almost always has too many pixels in it for onscreen display, and as a result, its file size is usually pretty hefty for emailing. Often, you need to make two copies of your photo for the two different uses.

This section gives you a brief introduction to both screen and print resolution and explains the decisions you need to make when using the Resize Image dialog box. You’ll also learn how to add more canvas (blank space) around your photos (to make room for a caption below a picture, for instance).

Tip

If you want to know more about resolution, a good place to start is http://www.scantips.com.

Resizing Images for Email and the Web

When your photo is destined for viewing onscreen, it should have enough resolution to be clear and easy to view without being oversized. Have you ever gotten an emailed photo that was so huge you could see only a tiny bit of it at once? That happens when an image isn’t optimized for viewing on a monitor. Today’s multimegapixel digital cameras spew ...