If you emphasise something only by a change of colour, the emphasis could easily be cancelled out by any of the following:

• Colour blind (10% of the male population)
• Low vision
• Black and white print-out
• Washed-out colours on a projector
• Badly calibrated monitor

The solution is to emphasise in 2 or 3 ‘channels’ – colour, contrast and symbol.

Here’s an example of what happens when you highlight something important in a document or a web page and what information survives when you print it in black and white.

Colour alone, meaning is lost

Colour and contrast – better, but still room for confusion

Colour, contrast and symbol – meaning survives intact