"How to" Guideline series is coordinated by Helen Mongan-Rallis of the Education Department at the University of Minnesota Duluth. If you have any questions, comments, or suggestions to improve these guidelines please e-mail hrallis@d.umn.edu.

Resizing Images

Created by Helen Mongan-Rallis. Last updated: January 20, 2008

Photos taken with digital cameras or scanned from a print can be very large. While this is desirable if you wish to print the photo, it can be a problem if you want to share the photo via email or on a web page. These guidelines are designed to help you resize images for email or for posting on a web page.

Why resize?

• For email:
  • Most email accounts limit the size of files that can be sent and received.
  • Even though you may have a high speed connection, recipients may not, and it is very frustrating to recipients to have to wait for a long time for large photo attachments to download (especially where users pay per minute for Internet connections!)
• For displaying on web pages (including sharing images with classmates within an online course management system such as Moodle, WebVista or Blackboard).
  • So that web page loads quickly (the smaller the image size, the quicker the page will load)
  • So end users can see the entire image on one screen without having to scroll

What size is best?

• General advice: no larger than is necessary users to see the detail that is required for your intended purpose
• Most monitors display images between 72 - 93 pixels per inch (ppi). Thus you should resize your images accordingly. e.g. digital cameras are typically set at 150 or 300 ppi. Thus you should resize your images to between 72-93 ppi before emailing them or displaying on a web page. (Learn more about image resolution)

Free tools for resizing images

Images can be resized using a wide variety of free applications as well as costly ones (such as Adobe PhotoShop). For most users seeking to share images via email on on a web page, using one of the free applications is all that is needed. Some suggestions are:

1. Resizr.com: Quick, easy resize online without downloading an application (cross platform). See also: Helen's basic guidelines for using Resizr
2. Windows XP Image Resizer (for Windows users only)
3. Mac OSX only:
   1. iPhoto
   2. Email photo to yourself using MacMail: attach image to an email, and then select "medium" or "small" from the drop down menu at the end of the email to resize the image
4. Gimp: free application with versions for both Mac and Windows. This powerful tool enables a wide variety of options for editing digital images, in many ways similar to the commercial Adobe Photoshop (learn more about Gimp).

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