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Did you know that something over 5% of your readers are colour blind? As a colour-confused editor, David Dorn has a few tips for you!
DO provide ALT="..." text for all your images. If a user cannot understand your image they can reload with images off. Consider using JavaScript MouseOver events to provide status-line descriptions of images- especially maps and navigation bars.
DON'T use red / green / brown / grey / purple next to or on top of or changing to red / green / brown / grey / purple.
DO have a strong, bright contrast between foreground and background colours- not only for your page text but also in your images. Even totally colour blind readers can differentiate similar colours which contrast bright with dark.
DON'T use colours in images to denote special areas, such as bar charts, maps and navigation bars. Consider using textures or line shading instead (try the 'paper' or 'pattern' function in your graph or painting program). Alternatively, provide additional written labels.
DO use blue, yellow, white and black if you really must use colours to distinguish items. These combinations are less likely to be confused than others.
Check out how your web page fares for people with various different forms of colour blindness here
