1. A method of displaying an image on a screen in a cockpit of an aircraft, the method comprising: controlling a background image on the screen in the cockpit to be displayed at a first mean luminance, and subsequently controlling at least two zones of the background image to be displayed at a non-zero second mean luminance that is less than the first mean luminance while controlling a remainder of the background image to be displayed at the first mean luminance, the at least two zones of the background image being determined independently of the background image, the at least two zones being separate and independent from each other; and wherein at least one predetermined pixel of a pattern is switched off in each occurrence of the pattern that is repeated to form the background image at least throughout the at least two zones.