For example, bright red and blue contrast greatly in terms of colour, but very little in tone. A difference in tone is usually more important than a colour difference. Yellow seems to be a particularly easy colour to see and is often the last to be 'lost'. It stands out in many situations, especially against black. Red stands out in good lighting conditions, though soon disappears as light fades.
Shiny surfaces reflect light in a way that can be confusing to the eye.
2.2 Labels and instructions For signs and displays, single upper case letters are easier to read than single lower case. However, sentences in mixed case are easier to read than sentences where the words are either all upper or all lower case. The letters used should be without ornamentations, i.e. sans serif. It is also important with signs and displays not to leave large spaces in the text. A number of visually impaired people have difficulty in scanning text and can lose their place or go to a new line when they reach a large space.