Website images that simply contain text make very bad links. An example of this can be found on the CBC‘s website. Notice the navigation elements on the left side of the page are images. There are several reasons why this is a bad idea.
The most obvious reason is that these images do not adjust their size with the font settings of the viewing browser. Modern monitors can be set to very high resolutions that can make small images next to impossible to read. If these images had been normal text the browser would render them in scale with the rest of the text. This is especially important to people with eyesight problems who set their browser font to be very large.
Secondly, the text in these images cannot be searched. For example, if you are viewing a site with hundreds of image based links it is not possible to use the searching features of your browser to find links containing certain words. Of course, a real website is probably not going to have hundreds of image based links but the principle is the same and is closely related to my main reason for writing this article which comes next.
All Mozilla based web-browsers (Mozilla Navigator, Epiphany, Firefox, etc) allow the user to simply type the text and the browser will highlight the link that matches the text. The user can simply press enter to follow that link. I encourage everyone to try this out, it is a real time saver. With this feature well designed websites can be navigated without reaching for the mouse. Off hand I don’t know if there are non-Mozilla based web-browsers that have a feature similar to this.
There are many good reasons to use images on a website. Replacing the browsers text rendering is not one of them.