To ensure that the information in an image is conveyed to everyone, colour should be used only in addition to a text description. In the example of the colour-coded bus timetable, the name of each bus route should be displayed in addition to using different colours. Alternatively, different patterns or differences in font may be used to convey differences, although this would not be conveyed to a screen reader. Whilst providing an alternative text description should avoid these problems, do not refer to colour alone in the description (e.g. "the red line indicates...").
Whenever colour coding has been used to convey information, make sure there is another means of conveying the same same information (such as a text description, or different patterns, or differences in font etc.).
No example is available.