Color Blindlness

Making the web accessible to persons with disabilities should be of paramount importance to web designers, especially those who design websites for public organizations, such as schools or government agencies. One facet of accessibility that is often overlooked, but is very important, is that of colorblindness. Since web designers make extensive use of color in their pages, both for design and functionality purposes, they need to have some basic knowledge of different types of colorblindness and how these might affect the usability of their site by people with any of these conditions.

People with colorblindness can experience varying degrees of red, green or blue deficiencies, meaning they cannot perceive these colors as they are being reflected back to their eyes. In one extreme form of colorblindness, rod monochromacy or achromacy, there is no perception of color at all.

When designing web pages, it is important to understand what someone who is colorblind sees when they look at your pages. A useful tool for this purpose can be found at http://www.vischeck.com. This website allow the user to check any image, graphic or webpage under conditions perceived by each of the three main types of colorblindness. Another tool available on this website allows the user to correct images for colorblind users. This process is called “daltonizing” and can be found athttp://www.vischeck.com/daltonize/

From a design standpoint, it is best to avoid problems of colorblind accessibility from the outset. Try not to make color the only means of emphasizing text or navigation tools. When color is used, offer an alternative way of getting the information from the text or graphic. Incidentally, when web designers take these thing into account for colorblind users, other users with visual impairments will benefit as well.